secure-cookies: Allow to use secure HTTPS cookies (Django setting)

Cf https://docs.djangoproject.com/en/1.4/ref/settings/#std:setting-SESSION_COOKIE_SECURE
Make code more robust to bad input (for case where DB was populated with string None)
Increase randomness of course name in testcase
Fix BulkAssertionMixin so that it actually asserts the truth/falsity of the contained assertions
Bump version of PyContracts so that it will disable the 'check' function
Teach mongo_connection to retry read operations in the face of AutoReconnect errors
Allow Timedelta and RelativeTime fields to handle from_json being passed timedelta objects
Put student profile third party auth behind a feature flag
Use split to test views
Fix acceptance tests to work w/ split
11300
Fix unit tests for generated
course ids.
Make xml exports more comparable by sorting and indenting json
Export xml from the destination store during cross-modulestore import/export tests
Make Studio CoursePage objects generate the correct CourseLocator based on whether the DEFAULT_STORE is set or not
Inherit from JSONField rather than Field for json-based fields
Merge pull request #5249 from edx/split/view_test_setup

Split/view test setup
Update djpyfs

And move from base.txt to github.txt
Tests for mobile api
update discussion blackout setting warning (TNL-442)
Merge pull request #5406 from edx/dcs/mobile-api-tests

Added tests for mobile API