WIP cropping user images

this is done client side using canvas
the output data is being added to the value of the image attribute in a hidden form field.  We could not get it to submit using the normal django form submission, an error saying the field is required is returned on submit currently.

current bugs:
if the user adds an image that is very large, it will not be cut off from the canvas element (this should be changed in the custom.js file)

maybe try a charfield input type to avoid django image checking
[example](http://stackoverflow.com/questions/17173680/uploading-javascript-generated-image-to-django)