Modify subscription before authorised
Modify subscription before authorised

It was reported that when the riak db is unavailable,
the admin cannot change the subscription status.
This is because the exception raised trying to
reach riak prevents subscription() being called.
As subscription() only edits local data, do it
first.

Fixes: #558

Rhizomatica/rccn,Rhizomatica/rccn,Rhizomatica/rccn,Rhizomatica/rccn,Rhizomatica/rccn