Users can now create an OAuth2 application limited to a certain Local

Site. The application creation & change forms now expose the

local_site field. This field is disabled in the change form and all

changes to the field will be discarded so that users cannot force change

the value by crafting their own requests.

Created an application limited to a Local Site via the form in "My

  Account".
Ran unit tests.
Verified local sites that aren't accessible aren't rendered to the

  HTML.