TpBaseConnectionManager: ref the CM once per Connection
TpBaseConnectionManager: ref the CM once per Connection

Some Salut test failures can apparently cause the Connection to outlive
the CM, causing a crash when it emits no-more-connections.

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