Simple port of Class2Go's chat feature

Embed a chat widget (much like the calculator widget) into the
courseware. To use, you must point it at an ejabberd box,
configured as `JABBER_DOMAIN` in the settings.
Move Candy.js files to new vendor/ directory
Remove additional jQuery include

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

Ensure that the chat connection settings are generated properly for
the template context.
Add setting to enable/disable chat site-wide

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

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.
Chat rebase, test update

Rebase on today's master and update to unit test to include settings
where needed.
change models to filter by course
Implement next generation modulestore

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
Make tests not msec time sensitive
Merge pull request #52 from edx/nate/simple-chat

Simple port of Class2Go's chat feature
set django-wiki to its most recent version
Ensure kvs up-to-date if code accessing it.
Merge pull request #445 from edx/adam/fix/wiki

set django-wiki to its most recent version
Move default set_many impl to xblock
Merge pull request #394 from edx/fix/foldit-leaderboard

Fix/foldit leaderboard
Add feature showing current score next to problem title
Resolve issues with persistence and sequential bar
Attempt to fix video test
Fixed two other tests