First audits for scope.

Finished users_controller and analytics_controller
Updated Badges scope

Second commit, updated badges_controller with new scope and filter for staff
Added challenge grades controller scope adjustment

Also need to consider whether students should have access to the 'show' view as well.  If not, we can change the filter so that it is only 'ensure_staff?' instead of being followed by exceptions.
Fixed challenge_grades_controller

challenge_grades_controller now unfilters index so students may see the index and show views.
course_memberships controller

added filter for staff and new scope for destroy method
Deleted a swap file to prepare work again.
Criteria controller done

altered criteria controller for scope
Criteria levels controller done

added scope changes to criteria levels controller
Earned badges scope updated

Also updated a number of method calls to current_course
Recommended fixes

completed recommended fixes.  These should be done now, except for the users controller, which I'm a bit confused about what I should do with it.
Last fixes from Cory's recommendations.

Removed cruft from users controller, checked in clean schema file, updated criteria controller scope.
Number of controllers updated.

Continuing update, will apply fixes after these commits have been reviewed.