Group based permissions are currently ignored on node forms

#1278060: Move "Administer OG menus" to OG roles/permissions added OG based administer og menu permission.
This is very nice, but doesn't do anything on node creation.

Ideally we'd want it to get it's context from the url.
The OG readme has info on how to do this. Basicly its ?gids_group[]=123 (where 123 is the group id).

Placeholder issue, a solution will be provided soon.