POST EncodedVideo set

EncodedVideo part of the upload. Complete EncodedVideo dicts may
now be uploaded. Rejects all EncodedVideos of a Video when there is
an invalid EncodedVideo. Does not reject other Video when a different
Video is invalid. Currently, EncodedVideo cannot be updated, they can
only be created.

Other notes:
-Added django-debug-toolbar==1.2.1
-constants.py has been reorganized