LMS: add CSRF token to register form
Add Neurolit to AUTHORS file
Set empty aws credentials to None.
Changed create_enrollment to create_or_update_enrollment
all CourseEnrollment modifications route through create_or_update
purchased_callback now uses the change_mode method
Response to CR
response to CR
sending template pdf with certificate request
fixing some typos
Teach OEE to consider old task_states when trying to recover from an xml mismatch
Centralize to a single GradingServiceError, so that it's caught when expected
Small fix
Assign a score of 0 to tasks with no attempts
Use correct set of OpenEndedChild states
Merge pull request #1686 from cpennington/hotfix-max-empty-sequence

Assign a score of 0 to tasks with no attempts
BLD-193: Add template for checkboxes to studio.
fix spammy log messages from course_id tracking in CMS
fix emission of enrollment events from the CMS

I suspect there are very few circumstances that an enrollment event is emitted from the CMS, but if it ever were to happen, it would bomb out because the "crum" middleware is not used in that app.  We are hoping to replace this request caching hack in the near future, but for now it is the best option we could come up with.

I noticed the stack appear when I created a new course in my dev environment.  Presumably the course author is automatically enrolled in the course, which, causes the tracking code to bomb out.  Luckily we catch the error and just log it, but we really should be capturing this type of enrollment event.
Merge pull request #1678 from mulby/gabe/fix-cms-course-id-tracking

fix spammy log messages from course_id tracking in CMS