The dbus_bus_get() function returns a shared bus connection that
all libraries in a process can use. You are forbidden from calling
close on this connection though, since you can never know if any
other code might be using it.

Add an option to use private dbus bus connections, if the app
wants to be able to close the connection.
Signed-off-by: NDaniel P. Berrange <berrange@redhat.com>