Flagging/unflagging is done by issuing a PATCH request on a thread or
comment endpoint with the "abuse_flagged" field set.

This implements the "following" value for the "view" query parameter on
the thread list endpoint.

Fixes tests, adds internationalized strings for new state tooltips, corrected tooltip javascript, etc.

* Delete reverification templates
* Delete photocapture.js
* Delete unused "name change" end-points
* Rebuild the reverification views using Backbone sub-views
* Stop passing template names to the JavaScript code
* Avoid hard-coding the parent view ID in the webcam view (for getting the capture click sound URL)

Iniital refactor of capa styling for basic checkbox and multiple choice problem types, including additional comments to sass styles

ECOM-1523

Following are done in this PR
1-The controls to edit the form fields were hyperlinks, added button and required css to
  make it look like hyperlink.
2-label added when swap to combobox
3-Non breaking spaces added with dashes.

The payment buttons now match the style of the verified upgrade buttons.

XCOM-422

Add more extensive testing

This will allow clients to determine what actions (e.g. following,
endorsing, and editing content) a user can take on a piece of content.

The comments service rejects whitespace-only content for certain
strings, so the discussion API should also reject such content.

removed JavaScript function specific to the upsell toggle
removed bok choy test
Removed all referenced to toggleExpandMessage()

Some old threads do not have the pinned field set, which the thread
serializer should handle.

The rendering in this commit does not prevent MathJax content from being
rendered as the discussion JavaScript code does.

Extends the common capa response types (string, numeric, multiple
choice, checkbox, dropdown) with feedback and hint
capabilities. "Feedback" refers to feedback shown to the student when
they check the problem, looking at their specific answer. "Hints"
refers to a Hint button in LMS which the student can click at any time
to see hints for that problem. The implementation extends the markdown
syntax to include feedback and hints. There are new Feedback-and-Hint
specific templates in Studio when the author clicks to add a new
problem.

Caches all permissions per user per course. Adds caching functionality to has_permission and replaces all instances of cached_has_permission with has_permission.