[Rails 4] Remove attr_accessible
Use UTC timestamps to sign requests to AWS
Relax model validations
Use keys from carrierwave_direct uploaders if present
Fix 404 errors due to relative paths
Escape URL strings for signing
Support for custom headers
Fix broken resume + progress after resume
Don't pause/resume completed chunks
Allow association options for uploads
Fix exception on single part uploads
Fix on_complete callback never getting hit
Debug upload exceptions
Add backend error translations and properly return them to client
Merge pull request #16 from artem-mindrov/master

Rails 4, i18n and more fixes & changes