Fixes for MOB-836 and MOB-766 and MA-96.
Add the ability for course staff to specify a Survey and make it required so that a student must fill it out before starting the course
Merge pull request #5799 from edx/hotfix_candidate/2014-10-30

Merging Hotfix candidate/2014 10 30 as per release process
Add warning about sensitive info in course export

DOC-977/DOC-991
Merge pull request #5818 from edx/release

Merging latest updates to release
Update change log for export security warning

DOC-977
Ignore errors during cleanup of course export command.
Merge pull request #5811 from edx/carol/docs/DOC-977

Add warning about sensitive info in course export
Merge pull request #5820 from rocha/dont-raise-error-on-course-export-command-cleanup

Ignore errors during cleanup of course export command.