Move vendor javascript into common/static/js/vendor, so that they can be shared between the CMS and LMS, and create an html template that includes all of the vendor js needed for the courseware

* Note: This doesn't run yet
* add config file for lms on mongo
* Some comment additions and cleanups

Get the video module pointing to the correct static files directory, without relying on get_html replacement

Split out code to replace /static urls in get_html into a separate module so that it can be used in CMS previews

Uniquify js fragments pulled from XModules, and load both XModuleDescriptor and XModule js into the cms

Add tests for the edit page for the toy course, and make sure that exporting to github sets up the git repo properly

Remove the live preview code from the html and raw modules, in preparation for updating the preview on save

Log error messages when failing to parse xml from a string that contain context of where the error occurred in the string (in definition_to_xml)

Escape characters from raw xml data going into the text box so that the round-trip doesn't get rid of neccessary xml escaping

Add feature flag for disabling course start dates

Conflicts:
	common/djangoapps/student/views.py
	lms/djangoapps/courseware/courses.py