Add a file uploader

[seancdavis]

While this is rather specific, I want to start somewhere, and this somewhere is by uploading to S3.

So, we'll build an uploader. We could even add some styles.

What we want to give the developer control over is:

• Their S3 keys
• The route to post to after upload is complete
• The sizes of images that are to be resized

A few additional notes:

• Eventually we will move to supporting other destinations.
• We won't support a manual cropper right now, but that's certainly something that could come into play in the future.
• The last comment (auto-sizing) would require tapping into ActiveRecord and also having something like DelayedJob configured.

I'd really like to implement all this, but this feature comes with the caveat of using CarrierWave Direct to S3, and then offloading processing to a DelayedJob background process. This is more specific than I want to be, but it gives us a place to start, which I like.