Updates Studio's visual styling of action buttons on components and static pages 

Modify jquery.timeago to better support i18n

Markhoeber/documentation/stud 1130

Fixed flaky test for instructor command openended_post.

Update tolerance information for Numerical Input problems

Correct three typos in video documentation

Allow user with BetaTester role correctly use LTI. BLD-641.

The submission time is serialized into json and sent to xqueue. Previously the
whole json body argument to send_to_queue() was being matched. Sometimes the
time calculated in the test would differ slightly from the time calculated in
send_to_grader() and the test would fail. This fix tests individual fields of
the body argument to mock_send_to_queue() instead.

Use subprocess.STDOUT, rather than sys.STDOUT to rebind stderr

i18n xmodule/course_module.py

Persist speed preferences between videos.

Added a .po segmenting tool

Use the configuration more, and we don't need to delete files we're
about to create.

Messages can be segmented into different .po files based on the location
of their occurrences.  This is so Studio strings can go into different
.po files so we can direct Transifex workers to the LMS strings we
really need done.

Bok choy tests output XUnit reports

Markhoeber/documentation/release notes 1 23 14

Remove comment for how to install PIL

LMS-1747

Remove CONTRIBUTING.md

resubscribe feature for notifier

Merge "video sources" and "download video" into the same field

adjusted unit_spec.js to reflect new HTML structure, and corrected screenreader label for delete button

Github includes a "Please review the guidelines for contributing
to this repository" link when creating a pull request, and it links
to the Markdown version of this file, which is annoying. Removing
the file should redirecto the link to the reStructuredText version
of this file.

We use Pillow now, which can be installed via PyPI

Enable microsite tests

Make video debug messages consistent.

Move microsite test assets to common/test

Rename helper method to not have test in the name
Rename test css file