Update NEWS file.

[ci skip]

* 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

When a matcher uses both `allowing` and `rejecting`, and validation fails,
`@missing_rejected_types` might still be `nil`.

When a matcher only uses either of the two, a part of the message is `nil`.

[fixes #2016]

[fixes #1932]

This was really confusing to me, and I think this small change would help to clarify what's going on without having to trace through the code.

Fixes #2130.

Fixes #2130.

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]

Update NEWS.

[ci skip]

Adds failing spec to command line dup check

[fixes #1670]
[fixes #2169]

`Paperclip::Storage::Fog#host_name_for_directory` assumes a String-like
object is set and doesn't check if `@options[:fog_directory]` is
callable, while `Paperclip::Storage::Fog#directory` does. This extracts
a new method with the condition and refactors the other two methods to
call it.

Fixes #2018, #2093.

This configuration constant was useful for supporting different versions
of AWS SDK. We don't any longer, and we can set the value directly.

[fixes #2148]

* `AWS::Core` is an AWS SDK v1 API, we can drop it
* We don't use the "I attach a" cucumber step

Brings back warning on not supported SDK versions.

Related: https://github.com/thoughtbot/paperclip/commit/25be0b25d67923e28419c6146e8f8307741a974b#commitcomment-16831800

We don't support AWS SDK v1 any longer.

Drops Rails 3 branches.

[fixes #2101]

Rails 3 is not supported anymore. We can safely remove mentions and
snippets for it.

Drop unused variable definition (`options`).

Update NEWS.

[fixes #2134]
[ci skip]

Ref: https://github.com/rails/rails/commit/2386daabe7f8c979b453010dc0de3e1f6bbf859d

Specifically:

> Chains of callbacks defined **with** a `:terminator` option will
> maintain their existing behavior of halting as soon as a `before_`
> callback matches the terminator's expectation. For instance,
> ActiveModel's callbacks will still halt the chain when a `before_`
> callback returns `false`.

In terminator callbacks, the `result` value changed to be a lambda now.
This change reflects that, updating the terminator to compare the result
of the block to `false`.

Also:

* Removes Rails 4.1 branch (we don't support it anymore)
* Rewrite for legibility: change `unless` for `if`

- Also bump Travis Ruby 2.2.x version to 2.2.4

We found that uploading large files to S3 would result in a socket error
("connection reset by peer") occasionally and lately much more
consistently. In researching this I saw that many people got this error
when uploading too large of a file without multipart chunking. I would
have assumed fog did this automatically but the default chunk size may
be too high. In order to address this I wanted to drop the chunk size to
100MB.

Rather than hard-code this I opted to expose a `fog_option`
configuration option that lets me pass any additional options I want to
the fog's `#create` call. This is similar to the `fog_attributes` option
implemented in CarrierWave which [addresses the same
problem](http://stackoverflow.com/a/11867978/201911).

We've been running this now for a week in production and it seems to
resolve the issue.

https://github.com/thoughtbot/paperclip/pull/2135

The MD5 sum of an attachment is only necessary if the model has a corresponding
_fingerprint column. If this column is absent, there is no need to calculate the
MD5, which can be an expensive operation for large files.

Accomplish this by deferring the fingerprint calculation using a block. If the
_fingerprint column is absent, the block is never called, and the calculation
is avoided.

These variables were introduced in:
https://github.com/thoughtbot/paperclip/commit/6ea7c26512434a
but their usage were canceled in:
https://github.com/thoughtbot/paperclip/commit/c740fb171fe

Extract another repository only concerned with locales:
https://github.com/thoughtbot/paperclip-i18n

A user of paperclip might choose to add `paperclip-i18n` as a dependency
for their application, or copy over the related locale file into their
project.

This is a first step in splitting some parts of the codebase into other
projects. Simple and relevant contributions like new translations might
get lost in the shuffle of dozens of PRs awaiting for approval, that
take time to review and merge.

Locales are a simple enough problem to be handled in an external
repository, where tests for consistency across translations run in less
than a second, and PRs can almost trivially be merged in.

the name string is used multiple times in interpolation so storing it reduces object creation

this commit primarily uses frozen strings to reduce object creation during interpolation.
the :basename method now uses File.basename(file, ".*") rather than a Regexp. basename may be called multiple times.

by using the attachment name (symbol) and Class as keys we reduce the number of Strings created before hitting the cache