CameraMenu: use empathy_camera_monitor_new()
CameraMenu: use empathy_camera_monitor_new()

We want to get a new object so that we get ::added upon
construction for all the cameras. With _dup_singleton() we may
get an existing object, which would have already fired the
initial set of ::added signals.

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