add dummy FEEDBACK_SUBMISSION_EMAIL for debugging
change FEEDBACK_SUBMISSION_EMAIL to @example.com in dev settings
Add filter for playback rates.
Merge pull request #673 from edx/hotfix/adam/help-modal

Hotfix/adam/help modal
Merge branch 'release'
Shift enroll/unenroll logic to CourseEnrollment model, add is_active and mode.

Features coming down the pipe will want to be able to:
* Refer to enrollments before they are actually activated (approval step).
* See what courses a user used to be enrolled in for when they re-enroll in
  the same course, or a different run of that course.
* Have different "modes" of enrolling in a course, representing things like
  honor certificate enrollment, auditing (no certs), etc.

This change adds an is_active flag and mode (with default being "honor").
The commit is only as large as it is because many parts of the codebase were
manipulating enrollments by adding and removing CourseEnrollment objects
directly. It was necessary to create classmethods on CourseEnrollment to
encapsulate this functionality and then port everything over to using them.

The migration to add columns has been tested on a prod replica, and seems to be
fine for running on a live system with single digit millions of rows of
enrollments.
Merge pull request #651 from edx/ormsbee/enrollment_modes

Add mode and is_active to CourseEnrollment, shift enrollment logic to model
styling of peer review interface for students along with minimal adjustments to the staff grading interface as well. added internationalization of peer grading strings.
Create Course Modes django app
Initial migrations for course modes
updating help for --course
Merge pull request #666 from edx/jarv/add-get-grades

adding django-admin commands to dump grades to a csv file
Add admin site for CourseMode
Merge pull request #676 from edx/diana/course-modes

Add Course Modes to LMS
Merge pull request #657 from edx/zoldak/fix-i18n-enroll

The enrollment_action value enroll should not be translated.
Fix error seen in combinedopenended modules
Merge pull request #681 from edx/sarina/hotfix/fix-combinedopenended

Fix error seen in combinedopenended modules
turn off i18n
Merge pull request #683 from edx/adam/turn-off-i18n

turn off i18n
turn off i18n