Initial filled out version of the Add Asset form.
Rename argument for consistency
Remove 'resolution' key from Asset object.

Since we're not actually using resolution for anything at this point (it's not saved to the database), it's wasted. Awaiting further clarification.
Preliminary Add Asset functionality.

Actually adds to the database now. However, we're using a regular POST form to create the new asset and return a redirect back to the index page. Uploading files with Backbone to an API is apparently tricky and there are complicated best practices I don't fully understand yet.