devices in sip_auth are deleted on blocking_refresh

devices in sip_auth are deleted when blocking_refresh is called or when registrar app starts.

the problem is with remove_aggregate_devices, the clause "orelse" causes all the devices to be deleted.

also reverted the order to remove/add instead of add/remove
Merge pull request #173 from lazedo/patch-1

devices in sip_auth are deleted on blocking_refresh: wow nice find that's been there a while now... thanks!