tp-chat: remove chat-state-changed-empathy signal
tp-chat: remove chat-state-changed-empathy signal

https://bugzilla.gnome.org/show_bug.cgi?id=675807

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