S3 Uploads Angular directives + ENV vars for S3

This feature is not complete yet, but I was at a good stopping point so I decided to pull in as-is to show others and give @simonv3 a chance to see what's going on with the visual aspects of the feature.

## What's New?

 * Finally got S3 working with Angular / Rails / Permissions
 * Added `/pages/test` for front enders to test their stylistic changes to the NgS3Upload directive.
 * Moved AWS secrets into env vars. See README.md changes.

## What's Next?

 * Need to get paperclip working on the attachments model
 * Probably need to get sizes working, although I'd much rather just get it working right now and polish it up later.
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