Automatically authorise apps

Until now, when you use any app for the first time, you 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.
Merge remote branch 'origin/master' into automatically_authorise_apps

Conflicts:
	app/views/doorkeeper/authorizations/error.html.erb
Merge pull request #48 from alphagov/automatically_authorise_apps

Automatically authorise apps