tp-chat: stop using the contact factory when building message
tp-chat: stop using the contact factory when building message

Messages are now synchronously proccessed so we don't have to keep an internal
queue of messages being prepared.
We also need to complete the preparation of the EmpathyTpChat feature in idle
as it's now prepared synchronously as well.

https://bugzilla.gnome.org/show_bug.cgi?id=675597

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