Added comments and add explicit ordering to this method, which makes the result deterministic and resumeable should an error occur mid-way. 

As values in set are strings - check is unnecessary.

Saving instances causes memory leaks in development mode in rails.

It's Paperclip's responsibility to escape special characters from the URL to make sure that it's comply with standard.

Closes #577, Closes #563, and reverse my judgement on #482.

It was working fine for me locally

fixes #588 . Attempt to log warning message when 2 models use same attachment name with default url interpolation

There was an issue on assignment another S3 attachment object to another object whereas calling #to_file on S3 attachment will create a Tempfile, which would then having a different file name than original version.

By caching the filename first before calling #to_file, we're ensuring that filename is the original one.

Fixes #9

Thank you @Bonias for reporting in

Closes #590

This will make sure Interpolations is comply with Ruby's Object#hash

Closes #569, Closes #603

This test will generate a basic Rails application, include Paperclip
into Gemfile, and call basic `has_attached_file` in the model. This will
make sure that we're not messing up any of the configuration and
integration for our gem and the Rails framework.

Thanks @GMFlash!

Closes #586

Thank you @excid3 for suggestion.

Closes #582

We've ignored the lock file at 3f56e703, so we should remove it as well.