Merge release back to master

Add edX Pattern Library to edx-platform

[S&B] Remove ruby dependencies.

Updating forum buttons and overall icon cleanup

LMS: updating response status messaging

Release Candidate rc/2016-02-09

Remove duplicate staff debug acceptance tests

Ignore venv directory when running jshint on circleci

Ekafeel/discussion api namespace pagination

Ekafeel/deprecated advanced component types

Going to merge, "Remove concatenation of i18n strings."

Sass compilation is no longer dependent on Ruby, so we are
removing its dependencies.

Upgrade diff-cover.

Hotfix: ac-201

Correctly add profile image to edX header.

address mathjax rendering bug (TNL-4080)

Clear caches between tests for ModuleStoreTestCase/SharedModuleStoreTestCase

Make ensure_indexes mgmt cmd semi-idempotent.

MA-1918 returning None for courses with no handouts

Query counts already happen at the model and Python API test layers.
Having query counts in the HTTP API tests makes things more brittle
because that includes middleware that this code should not be aware
of. We don't want to have to revisit these tests every time
another piece of middleware is added or removed.

Remove flaky decorator from test_cancel_comment_edit