Moved crop updating to the API.

This whole "small chunks" thing is a lot more manageable. 

# Why
* The form was kind of shitty.

# What's changed
* Moved the crop adding stuff to the database.
* Now shows existing images.

![screenshot 2014-12-17 18 56 29](https://cloud.githubusercontent.com/assets/485583/5470722/72cf17da-861e-11e4-881e-6a63b8ab57dc.png)

# What's next
* Deleting already existing images if they're marked for removal.
* Moving things from the s3upload temp to the existing images array when uploaded.