IndividualManager: disconnect handler from aggregator
IndividualManager: disconnect handler from aggregator

Previously, the handler for
FolksIndividualAggregator::individuals-changed was never disconnected;
thus it could be called after EmpathyIndividualManager dies (if its
aggregator outlives it), and crash us.

https://bugzilla.gnome.org/show_bug.cgi?id=658340

Distrotech/telepathy-account-widgets,GNOME/telepathy-account-widgets,GNOME/telepathy-account-widgets,Distrotech/telepathy-account-widgets,GNOME/telepathy-account-widgets