Update build badge

* Only show build status for master branch
Show payment dialog when activating a private repo
Create subscription when payment is received
Remove dialog
Show price on payment form
Test against serializer
Create Stripe subscription with the correct plan type
Activate repo when Stripe subscription is created
Remove jQuery
Change email job to have high priority
Clear repos if any are missing information

* This will trigger a forced refresh and fill in missing in_organization
* and private fields.
Simplify SubscriptionsController
Add RepoSubscriber to handle Stripe and Repo subscriptions
Add ability to subscribe and unsubscribe
Use null, not nil, for default argument value