DeeServer instances stop shared GDBusServers

[Michal Hruby]

There's a call to g_dbus_server_stop in DeeServer's finalize method (which seems to be necessary to close the server's socket), but DeeServer is written in a way to share a single GDBusServer between multiple DeeServer instances (if they use the same address).

This of course means that if the sharing feature is used, the dbus server is stopped as soon as any of the DeeServers is finalized - as opposed to stopping it only after *all* DeeServers are finalized.