config refactor wip
merging from master
Uncomment thumbnail tests
Decorate test functions that require Pillow JPEG support
actually look for an image to verify that a thumbnail has been generated
Update pillow to 2.6.1
pep8 and comments
Split mongo support for libraries and Library XBlock
renmaing prod.py and setting more defaults
renaming to use underscores
Don't allow voting while the thread is closed

When someone closes thread there is still option
to add vote which cause error when click on add
vote button. User shouldn't be able to add vote
while the thread is closed.

TNL-152
Pin django-cas to hash
Move to github.txt and make editable
Add base support for cohorted group configurations

TNL-649
Add support for user partitioning based on cohort.

JIRA: TNL-710

IMPORTANT: this commit converts the course_groups
package to using migrations.  When deploying to an
existing openedx instance, migration 0001 may fail
with an error indicating that the CourseUserGroup
table already exists.  If this happens, running
the 0001 migration first, with the --fake option,
is recommended.  After performing this step,
remaining migrations should work as expected.
Add group_access field to all xblocks

TNL-670
avoid errors when forward-migrating course_groups after south conversion

JIRA: TNL-937
moving the convert_tokens function to a common file
fix export for openassessment drafts (PLAT-249)
Make changes to the Mongo modulestore format for asset metadata.
Move the asset types under a top-level 'assets' dict to allow for
future arbitrary asset types.
Change 'basename' to 'pathname', since the attr is for storing the path.
Merge pull request #6033 from edx-solutions/content-libraries

Modulestore Support for Content libraries (Part of SOL-1, SOL-2, SOL-3)