Hide errors from non-staff users

Feature/victor/bad content warn not error

Feature/victor/dark launch

* will avoid newrelic complaining
* NOTE: Is this what we want post-ship?
  - need some way of notifying instructors of problems

* pass user to check_course
* if dark launch feature enabled, users with staff access to course
can see courseware before start date.  Students still can't.
* tests.
* Remaining: enrollment view has custom access control.  Need to check it.

* Just log a warning and return a dummy url
* May want smarter checking later
  (e.g. would be nice to tell staff what files are missing.)

If there is a missing static file, don't break the server, just leave a ...

Spinner on waiting for queue

Kimth/lms coderesponse

Fix metadata inheritance

* bodyclass block got accidentally deleted

* with xml datastore, re-do all inheritance once the whole course is loaded

fixed course name title bar bug

Feature/victor/course grade detail

* need to actually return 404 codes to clients when DEBUG=False
* add option to make nose more verbose and drop to pdb on error

* dashboard links to gradebook and dummy grade summary page

* don't display thousands of '%' characters
* s/percentage/fraction/, since that's what it is

* also added todo about need for pagination

* required some refactoring in create_account() view

* also adds a comment to lms/urls.py

Did a quick security scan through views.