Added jsonable_server_error in common/util/views.py
Make CMS errors JSON-able if requested via AJAX
Make notifyOnError handler try to parse response as JSON
Adjust indentation to make coffeescript happy
Fix coffeescript issue on Linux

On Linux, coffeescript refuses to compile unless the `catch` keyword has an error
variable to bind to. On Mac, it works just fine either way. Go figure.
Merge pull request #233 from edx/db/ajax-server-error

Make server errors return JSON if requested via AJAX