[ticket/606] Dedicated permission for attaching language pack

[ticket/606] Dedicated permission for attaching language pack to a MOD/Ext

CUSTDB-606
Hm? 
`'S_IS_AUTHOR' => titania::$contrib->is_author || titania::$contrib->is_active_coauthor`
`'S_IS_TRANSLATOR' => titania_types::$types[titania::$contrib->contrib_type]->acl_get('attach_language_pack')`