types: Use dbus::Error instead of ()
types: Use dbus::Error instead of ()

dbus has an error type, we never seem to be using Err(()) so use the
proper error type instead.

Signed-off-by: Andy Grover <b7d524d2f5cc5aebadb6b92b08d3ab26911cde33@redhat.com>

agrover/froyo