Improve documentation for bok-choy.

Includes info about the serversonly/testsonly pattern, as well
as multiprocessing.

SEC-27: Escape json for Studio advanced settings

Remove chat feature

- Resolve SEC-27 by escaping course name in advanced settings
- Add escape_json_dumps to simplify escaping json in Mako templates

SEC-27: XSS/JS Error in Advanced Settings with invalid course name

SOL-1315: Add Cert Exception UI on Instructor Dash

Fix for flaky asset test SOL-1160

Fix flaky video test

Multi-process bok-choy tests

Fixed an incorrect revert

This includes:
* Ability to specify number of processes to run bok-choy tests in
* A forked nose commit to get the multiprocess plugin's logging to work
* A different plugin (xunitmp) must be used for pulling together xunit results

This works by:
* Starting the various servers that are needed for the acceptance test environment
* Running the tests themselves in multiprocess mode

Bug fix: Added test cases and updated course info view with exception handling

Changed command description texts to be sentences

TNL-3643

Fix an incorrect string format

This was originally contributed upstream by Stanford, circa 2013.

We neither use nor support this feature in its current implementation,
and in fact, we may never have used this production. Until recently, we
had additional chat/Jabber code [1] (in the form of a Jabber djangoapp in
LMS); context there suggests this feature may have never been more than
a prototype. The original author is no longer on the team, so I can't directly
confirm this on our end.

Do you use this feature?

Stanford had already abandoned this Jabber-backed chat implementation,
in favor of an IRC backend, by the time I joined the team in early 2014.

[1] https://github.com/Stanford-Online/edx-platform/commit/dbe52a6b133ab6ff637dea5324f7322da2909070

When I reverted the edx.org theme in 116ca291,
I reverted this line incorrectly. It should be like this.

Convert country to unicode before sending to segment

TNL-3725

Date summary blocks.

Fix bugs in course unenroll popup

Having the messeges embedded into onclick attributes was fragile because
it could break if the translated string contained special characters
such as single quotes.

Rather than trying to escape the special characters inside the onclick handler,
move the translatable strings into separate h-escaped data attributes and interpolate
the values in the (already existing) jQuery click handler rather than in the
inline onclick handler.

This makes the javascript code more consistent as well as fixes the problem
where the popup would break if translation included single quotes.

The string is passed through the JS 'interpolate' function,
which expects %()s style placeholders.

Hide Xblock due dates in studio for self-paced courses.

Enabled behind the
`SelfPacedConfiguration.enable_course_home_improvements` flag.

ECOM-2604

Removed read-only fields from enrollment admin

asadiqbal08/SOL-1292 Entrance Exam is not imported with an imported course

Remove flaky flag from profile bok choy test

Add a class to the course number in the page header to facilitate hiding it in a theme.

set max width for nav-account-user for long characters

The read-only protection is more hassle than it's worth when testing locally and on stage. It's a solution to a problem we don't actually have, so I have reverted the changes.

Updating edx-platform for XBlock#323