Next gen modulestore

Will/fix acceptance tests

Renzo/in context progress

Fix/foldit leaderboard

set django-wiki to its most recent version

Simple port of Class2Go's chat feature

A new modulestore backed by mongo that changes the data format to
facilitate easy versioning, sharing content between courses, and fast
lookup of course structure and Scope.settings data.

Conflicts:
	cms/djangoapps/contentstore/tests/test_contentstore.py

POST requests were claiming request.method == 'PUT'

Fix/vik/studio oe

Ned/studentmodulehistory cleaner command

So, changed handlers to look for either value.

Bug report: remove <?xml version..> tag

Fixes code_jail imports and draganddrop yaml

I18N work seems to have lost a very prominent space in the landing page

add a new django-admin command to dump out a course structure document. ...

https://edx-wiki.atlassian.net/browse/STUD-428

Rebase on today's master and update to unit test to include settings
where needed.

Only render the chat widget if both the site has enabled it in the
`MITX_FEATURES` and if the course has enabled it. In addition, fail
gracefully with a log warning if the `JABBER_DOMAIN` is not set, and
do not try to render the widget. However, do go ahead and render the
rest of the courseware.

To protect against chat blowing things up, we include a way to
enable and disable it on an entire site-wide basis.

Ensure that the chat connection settings are generated properly for
the template context.

jQuery already available across the whole site at the top level, so
no need to include it again specifically for the chat widget.