Activate empathy when clicking on a chat icon by asking the
ChannelDispatcher to open the conversation in the default handler.
Also, remove the Approver and Handler for now, since until
telepathy-logger is stable, this means Empathy won't see (and log)
those conversations. This means that empathy's blinky status icon is
back; we'll have to do something else about that.
https://bugzilla.gnome.org/show_bug.cgi?id=611610
Cache avatars to avoid having to re-download them every session.
We use a cache format that is compatible with empathy's, but we don't
actually use empathy's. This could be changed if we wanted.
https://bugzilla.gnome.org/show_bug.cgi?id=614974
Also reorganizes the notification layout to use an StScrollView; very
tall notifications are now scrolled instead of just taking up more and
more of the screen.
https://bugzilla.gnome.org/show_bug.cgi?id=608999
