Updated S3 requirements.

https://github.com/madewithbytes/us_ignite/issues/71

The requirements will handle any S3 integration of
the application.
Update production file storage settings to be S3.

https://github.com/madewithbytes/us_ignite/issues/71

Any asset in the server will be stored and served
from S3.
Cosmetic update on the class.
Add fabric mechanics to process static assets in S3.

https://github.com/madewithbytes/us_ignite/issues/71

Heroku will process the static assets and directly
upload them to S3.