Minor pylint/whitespace changes
Add serial commas to modulestore definitions
Remove traling commas to make json valid
Add docstring to CourseDescriptor.__init__
Remove noop if statement
Clean up variable naming
Make SessionKeyValueStore variable names clearer
Remove unused template
Handle edge case when trying to aggregate progress in an empty sequence
Make url matching regex flexible to allow for browsers that munged :// into :/
Fix SessionKeyValueStore.has to use the correct indexing value when looking up data
Retrieve location from self in CustomTagDescriptor
Make request.POST be only json content when using expect_json
Standardize on get_default_time_display
Add JSON encoder for datetimes to xml export

During policy export, we want to write any python datetime objects found
as iso timestamps, rather than throwing exceptions.
WIP: Use approximate comparison when checking for changes to start dates
Test start_date in course settings
Assert date equality directly, rather than by using a delta of 0
Remove extraneous test for already handled edge case
Make DraftModuleStore mongo only

DraftModuleStore was originally designed as a mixin, but never used that
way, and with the upcoming changes to use the versioned module store,
never will be. This changes removes a circular dependency between
mongo.py and draft.py.