Make the oa_access admin forms more easily alterable.

 * Put the 'gid' on the 'Team permissions' form so you can get info about the
   current space.

 * Make it possible to hide certain permissions by setting '#access' => FALSE
Merge pull request #35 from dsnopek/oa_access-admin-form-alterable

Make the oa_access admin forms more easily alterable.