Simple addition to allow procs in the fog_config_options (bucket-name, authentication, and host)

Travis CI deprecated and remove the rbx-2.0 alias after rbx project
merged stuff back to master branch.

Closes #678. Closes #450.

If a model has an existing attachment and styles, and later a new attachment is added (not just new styles), "rake paperclip:refresh:missing_styles" would crash with "TypeError: can't convert nil into Array".

#fingerprint now consistently returns nil before and after saving an attachment if the value can't be written to the db.

Add documentation for including `aws-sdk` in Gemfile

Add ':keep_old_files' option to `has_attached_file`

Set this option to `true` will make paperclip retain your file from the storage engine.

From https://github.com/pcreux/paperclip/commit/52374958ef83f1641cf008aead27c23b25fb842d

Conflicts:

	lib/paperclip/attachment.rb

This fixes #660

This is necessary so Gemnesium will be green.

Standardize strip with resy of application.  Without to_s, causes errors like "undefined method `strip' for image/bmp:MIME::Type".