Create a RESTful handle_cohort view method for GET and PUT/POST.
Use edx namespace for Backbone classes
Add tabs to the cohort editor
Share form between new modal and settings
Implement full new/save support for cohorts
Fix unit tests
Adjustments to markup and styles from PR review
Missed a comment in the PR review, removed unused classname
Don't allow renaming of cohorts
Changing classname of individual form field items