Closes https://github.com/thoughtbot/paperclip/issues/2253

2254 coverage (#2395)

* f(x): default to Paperclip::ContentTypeDetector

* fix: failures

* spec: cover consecutive periods

* fix: hound

* fix: hound

* Added support for aws-sdk-s3 gem which is now preferred way to interact with s3.

Reference: https://github.com/aws/aws-sdk-ruby/blob/master/V3_UPGRADING_GUIDE.md#library-maintainer

* Drop support for aws-sdk gem

There was a bug in the code where if you created a bucket the file would
get read but not rewind on the first pass through (when the bucket
didn't exist). So when we went into the retry logic the file would
already be read and zero bytes would get copied over from the file. This
fixes that by rewinding the file during the retry so it gets correctly
copied over the second time around.

Please see #2527 for details.

Remove the URI adapters. Few people use them by default and they can
allow insight into the internal networks of the server. If you want to
enable them, add (for example) `Paperclip.DataUriAdapter.register` to
your `config/initializers/paperclip.rb` file.

This is related to CVE-2017-0889.

Elsewhere fix CI: it's `s3.us-west-2` now, with a dot.

Thanks for the tip, @brendon!
https://github.com/thoughtbot/paperclip/pull/2331#issuecomment-262910522

Allows `s3_host_alias` to be set to CDNs which support S3 Bucket prefix.

[fixes #2287]

Bug introduced in 1c7d7f66

Per https://github.com/thoughtbot/paperclip/commit/1c7d7f66ceea27cfe604e3a13c2eb87df217d13a#commitcomment-18765681 request

[Amazon S3 Transfer
Acceleration](http://docs.aws.amazon.com/AmazonS3/latest/dev/transfer-acceleration.html)
enables fast, easy, and secure transfers of files over long distances
between your client and an S3 bucket. And
[aws-sdk](https://github.com/aws/aws-sdk-ruby) has allowed us to enable
this feature in version 2.3.0 (more detail is
[here](https://github.com/aws/aws-sdk-ruby/pull/1163)).

You can now pass a configuration option (:use_accelerate_endpoint) when
config Paperclip with S3. You can enable the [Amazon S3 Transfer
Acceleration](http://docs.aws.amazon.com/AmazonS3/latest/dev/transfer-acceleration.html)
by set this option:
```:use_accelerate_endpoint => true```

[fixes #2291]

* correct S3 specs to use the correct keys in the s3_credentials hash
* S3 tests work with a region that requires s3_domain_url

[fixes #1985]

Adapters now accept an options parameter, that currently specifies
the type of hash digest to use.  The default value remains MD5, but
can be specified to be any OpenSSL-supported digest.  The specs are
modified to reflect that.

The task just reassigns all of the attachments, thereby regenerating
their fingerprints.

[closes #2155]

* Add default `content_type_detector` to `UploadedFileAdapter`

Default `s3_protocol` used to be `http` when `:s3_permissions` are
`:public_read` (default), and `https` when `:s3_permissions` are
anything else.

With an empty String as default, if the page is served over HTTPS,
attachment URL will be HTTPS, and if the page is served over HTTP,
attachment url will be HTTP.

`public-read` is an authorization concept, independent form the
encryption of the HTTP connection used to read the file. As such, the
one shouldn't define the other.

[fixes #2038]

If `only_process` list is not empty, but it doesn't contain `:original`
style, original file hasn't been reprocessed and it's not needed to
rewrite/reupload it.

[fixes #1993]
[fixes #2046]
[fixes #1804]

There's a subtle difference between what `\Z` and `\z` consider the "end
of string" which is that the uppercase version allows a single trailing
newline:

```
/\Afoo\Z/.match("foo\n")

/\Afoo\Z/.match("foo\n\n")

/\Afoo\z/.match("foo\n")
```

* There is no need to pass options argument to UrlGenerator
* Houndci compliance

I recently implemented a custom processor that used the Exifr gem to
extract EXIF information from images uploaded to a Paperclip attachment.
Exifr's processor uses readbyte to parse the EXIF header, so it hit
errors when Paperclip's File-like object didn't have one. There's also a
test for this delegation.

I've also tidied up the README documentation for custom processors,
hopefully to be more clear than before. There was some duplicated
content between the "Post Processing" section and the "Custom Attachment
Processing" section, and those sections were separated in the file. I've
dedicated the "Post Processing" section to Paperclip's built in
thumbnailing processors, and made "Custom Attachment Processing" section
solely about writing & using your own custom processors. This should be
a more understandable progression, as built-in functionality is
discussed first & separately from extending Paperclip.k

- The uri io adapter now seeks for the content-disposition header
  if this is pressent the value filename is taken instead of the
  last path segment for the resource file name
- Fix style comments
- Applied the Tute Costa refactor to URI Adapter.
- Added entry to  the NEWS file.
- Removed editor tracking file
- Fix test cases

AWS no longer accepts `:aes256` as an encryption value and will raise
`Aws::S3::Errors::InvalidArgument` with the message `The encryption method
specified is not supported`. It should instead be `"AES256"`.

This commit makes no implementation change, but for those that use
source code and tests as documentation, it should help prevent
confusion.

* Add `read_timeout` option to `UriAdapter#download_content` method
* Default `read_timeout` is `nil`
* Update NEWS

* replaced if-not-blank with if-present

an instance of code was testing presence via `!a.blank?`. this is now
replaced with a more readable version: `a.present?`

* replaced 2 if-not-blank checks with if-present checks

* temporarily restrict travis

* reverted travis changes

* readded whitespace

Note: this is most likely not the way we want to test our matchers, but it
demonstrates the current issue.

Excessive logging can fill up disk space and become a denial of service attack, see https://cwe.mitre.org/data/definitions/779.html

This is part of the effort started at
https://github.com/thoughtbot/paperclip/issues/2199 to ensure the test
suite is green locally.

The attachment processing spec was failing since the setup required done
in a before block, namely a call to `rebuild_class`, was running
restricted to one of two contexts in the test file.
This was leaving the `Dummy` class in a bad state and affected other tests.

This PR moves the `before` block to run for the both of the contexts.

This is part of the effort started at
https://github.com/thoughtbot/paperclip/issues/2199 to ensure the test
suite is green locally.

The validators spec was failing since the setup required was missing a
call to 'rebuild_class' and leaving the Dummy class in a bad state.

This PR adds the call to the before block setup.

This is part of the effort started at https://github.com/thoughtbot/paperclip/issues/2199)
to ensure the test suite is green locally.

This spec was failing on obtaining a S3 instance with an `nil` region
key. Since `Aws::Resource` does a regex match against the region key
passed in, we would fail on `NoMethodError`.

This corrects the issue by setting a region key to an empty string in
the test setup.

[fixes #1932]

Currently paperclip fails with `NoMethodError` on `nil` when file is not
present. Since `nil` is proper response from fog on missing files, and
this method already returns `false` if any error happen (see line 178),
returning `false` here would be properly handled on client code.

[closes #2173]