NULLify proxies' dbus connection and daemon after emitting invalidated.
NULLify proxies' dbus connection and daemon after emitting invalidated.

This fixes fd.o bug #18845: the handle ref cleanup code needs to use the
DBusGConnection in response to ::invalidated being emitted, but if the service
fell off the bus the DBusGConnection was destroyed before the signal was
emitted.

Distrotech/telepathy-glib,Distrotech/telepathy-glib,Distrotech/telepathy-glib,Distrotech/telepathy-glib,Distrotech/telepathy-glib