The reason behind this I'm trying to use StringioAdapter inside the mailer, and it fails because `length` used in one of the `mail` gem:
https://github.com/mikel/mail/blob/master/lib/mail/message.rb#L1997

Also you can see that normally `size` has `length` alias, for example in a `StringIO` class:
http://ruby-doc.org/stdlib-1.9.3/libdoc/stringio/rdoc/StringIO.html#method-i-length

Let me know, if this change requires test case, I will add it.

As referenced in #1739

Just because the `Rails` constant is defined, it doesn't mean we're
actually in a Rails app. Since there are people who use Paperclip
outside of Rails, and there's no reason we shouldn't be able to run in
those situations. This commit checks for `Rails.env` instead of just
checking for `Rails` and assuming `Rails.env` works.

This reverts commit 06802254.

@see https://github.com/thoughtbot/paperclip/commit/804b4edc1d8d7ca9865170e34f26da7d66f6d0d5#commitcomment-8497017

Including + now.

Many people have complained that the Media Type Spoof Detection does not
work properly for their files. While whitelisting is available for some
files, it's not a general solution. This option leaves the "secure by
default" of the media checker in place, but allows people to turn it off
completely if they so choose.

Column-specific options can be specified by using its name,
for example:

```
t.attachment :avatar, created_at: { index: true }
```

Use proper name for zh-TW locale.

Use proper name for zh-CN locale

Add explicit unlink to intermediate files from processors.

Also, add integration tests for custom processor definition and unit
test for Paperclip.load_processor (thoughtbot/paperclip#1535).

... instead of `lib` of `lib/paperclip_processors`.
Fixes thoughtbot/paperclip#1534

Remove duplicated attribute :whiny.

documentation.

They recommend sending a block to the #read method to avoid loading
large objects into memory. See:
http://docs.aws.amazon.com/AWSRubySDK/latest/AWS/S3/S3Object.html

 as the former is deprecated and throws a warning.