Notification levels can now be set on the Project's main page

The notification settings for a project can now be set directly on the Project's page. The drop down list and the button label reflect the current level.

Saving is done via a remote form submission and if successful shows the user a flash message:

@DouweM can you please review my code. I gave my bestest effort to make in clean and readable.

@rspeicher hopefully we can include it with the 8.0 release, maybe?

/cc @darby