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 fixes to notes in #182

* use 'location' instead of 'id' in views.
* still need to change names in the coffeescript--quick fix didn't work

Victor/cms more auth

* add optional author_str param to export_to_github
* pass the django user info to that param

* add dummy has_access(user, location) method
* re-organize views by type of access checking needed.

* connect up views from student app
* Add initial @login_required decorators on the protected views
* Add tests for some of the basic functionality

CodeResponse for external/queued grading of student code

Victor/cms auth