DO NOT MERGE - mock out mongo modulestore

Mock the MongoConnection for modulestore tests
Clean up all modulestore testcases
Move modulestore config for tests to an importable location
Disable pylnt warning for lms imports in common tests
Refactor all testcases that loaded all xml courses
TE-610
TE-489

Conflicts:
	common/lib/xmodule/xmodule/modulestore/tests/django_utils.py
	common/lib/xmodule/xmodule/modulestore/tests/test_assetstore.py