We accidently were removing the ability for a service to do email auth
if it was a broadcast service with email auth. This fixes it.
Note, it might be up for debate later whether we let broadcast services
use email auth (I think we should) so this might change in time, but we
will fix this bug regardless.
Note, worth glancing at `SERVICE_PERMISSION_TYPES` which contains a list
of permissions that a service might have to make sure I haven't missed
any others. The one that looks potentially dodgy is the
`EDIT_FOLDER_PERMISSIONS` permission but I can't see this being used
anywhere in the API or the admin app so think it is likely now defunct
and a user level permission so we don't need to worry about it.
