Performance enhancements for unit tests
in test_contentstore, don't load the xml course if not necessary
Dont' need error check call in old mongo on this test
pylint cleanup.
Merge pull request #5560 from edx/benp/improve-pylint-violations

pylint cleanup.
Endorsement username shouldn't be broken

If we endourse the answer of the question in discussion
the username link that is created is broken whereas it
should point to the userprofile.

TNL-188
Merge pull request #5558 from edx/dhm/bug_index_count

Dont' need error check call in old mongo on this test
Merge pull request #5535 from edx/dhm/unit_perf

Performance enhancements for unit tests
Merge pull request #5540 from mlkwaqas/waqas/tnl188-endorsement-username-link-broken

Endorsement username shouldn't be broken
Change text of registration to enrollment