Add absolute_import future imports

Add absolute_import from __future__ so that pylint
does not fail and to achieve python3 behavior in
python2.

Reviewed-By: Christian Heimes <cheimes@redhat.com>
Reviewed-By: Alexander Bokovoy <abokovoy@redhat.com>

ipaserver/plugins/server.py

@@ -2,6 +2,8 @@
 # Copyright (C) 2015  FreeIPA Contributors see COPYING for license
 #
 
+from __future__ import absolute_import
+
 import logging
 
 import dbus