Updates to work on more-modern OSes.
Updates to work on more-modern OSes.

Firstly, it seems that ck-list-sessions isn't always accurate, so lets
get this data from `who` as well.

Next, we need to start passing in in DBUS_SESSION_BUS_ADDRESS
environment vars where required (or --address), so that applications
know which dbus session to talk to.

We also need to now be able to pull a DBUS_SESSION_BUS_ADDRESS when
all we have is an XOrg DISPLAY variable, so do that as well.

I'm *this close* to removing support for dbus-send which is really
painful to use compared with qdbus...

ShaneMcC/screenlocker