Handle OpenID errors for POST requests.

Benp/diff cover threshold2

Student profile CSV background task tech debt

ECOM-441

Ensure all user-facing cohort-related strings are internationalized

TNL-565

TNL-566

Some strings were missing i18n calls

When using -p, the underlying diff-quality command will pass that
number as a value for --fail-under.

For example,
  paver run_quality -p 75

Will pass 75 into the --fail-under switch on diff-quality.

Also upgrades diff-cover in order to take advantage of this funcitonality.

Update Contributing documentation with new PR process. OPEN-111

MA-81 Honor video download setting with VAL-enabled videos.

Studio: FIX - Course Rerun Outline Notification Icon Display

Update django-countries to 2.1.2, override country name for Taiwan

Removing the feature flags for new header and footer.

Clean up after track selection experiment

TNL-550

TNL-534

UX-1054

Fix acceptance tests

Updating lettuce tests.

Revert the deletion of the original edx header and footer.

Renaming old header and footers to legacy files.

Add IS_EDX_DOMAIN flag for header.

Updating tests and django main template.

renaming the header files for microsite backwards compat.

Removed Vitalsource e-reader information

Dashboard template cleanup

Make password reset endpoint CSRF exempt

Endorsement username shouldn't be broken

Performance enhancements for unit tests

Dont' need error check call in old mongo on this test

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

pylint cleanup.

Added handling in gitlog template for missing import logs

Consistently wrap the DataDog API to prevent logged errors & missing stats data

Upgrade pymongo