Automatically authorise apps

Until now, when a given user accessed each app for the first time, they had to manually
"authorise" (or "deny") "access" to the application. This is complexity
that doesn't do us any good, and probably confuses users.

Now, it will automatically be authorised.

@jystewart is [happy with this change conceptually](https://www.pivotaltracker.com/story/show/33452759) so this PR should be a question of functionality and code quality.