disable chat history menu item when there is no account. (bug #562554)
disable chat history menu item when there is no account.
(bug #562554)

svn path=/trunk/; revision=2265

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