Added paperclip:refresh:metadata and :thumbnails tasks, and a paperclip:refresh task to tie them together. Also, paperclip:clean checks validity of the attachment, not the whole model instance.

Calling #valid? on the model corrctly runs validations on the attachment. Calling #valid? on the attachment correctly runs validations instead of reporting only on current status.

Added reprocess! method. The rake task will actually reprocess the data it has now instead of ignoring it.

has_attached_file respects :whiny_thumbnails. Added validates_attachment_thumbnails which does the same thing.

Changed keyword-collection mimetype matching to regexp matching.

Added tests to prove that the new validation is working.
Added the public directory to .gitignore
Changed the upfile content_type code to assign txt files to text/plain mime type

Put merged tests in the right place.

Changed S3 URL generation to a manual interpolation instead of RightAws's public_link method.