Title-change for failure provides un-parseable json

In current trunk, when reporting a failed purchase, the returned JSON isn't JSON (as it is missing a comma):

It looks like this was introduced while adding the user_cancelled property. It's unfortunate that it's quite difficult for us to test reliably, given that our test runner doesn't execute JS.

Also, there is an inconsistency between: false and "False" being returned as values for different attributes ('successful' and 'user_cancelled' respectively). Looking at the SC code which does parsed_json.get('user_cancelled', False), I assume it should indeed be the json false, rather than a string.

STR:
(Note: I assume this is also reproducible with the SC client, but steps here aren't dependent on the client - feel free to update)
 1) Access https://sc.staging.ubuntu.com/subscriptions/en/ubuntu/maverick/+new/?archive_id=canonical-isd-hackers/internal-qa&arch=i386 (or relevant server) and cancel the purchase (if it isn't already),
 2) Use your browsers javascript debugger to copy the title (ie. for me it was: { "successful" : false, "failures" : "Error while checking or creating a LP person: [Errno 111] Connection refused" "user_cancelled" : "False"}
 3) In your JS debugger try to eval your json: eval({ "successful" : false, "failures" : "Error while checking or creating a LP person: [Errno 111] Connection refused" "user_cancelled" : "False"}) - you'll get a syntax error. Add a comma before "user_cancelled" and it will work.