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/advise/base.py

@@ -17,7 +17,7 @@
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
 #
 
-from __future__ import print_function
+from __future__ import print_function, absolute_import
 
 from contextlib import contextmanager
 import logging

ipaserver/advise/plugins/legacy_clients.py

@@ -16,6 +16,8 @@
 # You should have received a copy of the GNU General Public License
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
 #
+from __future__ import absolute_import
+
 import os
 
 from ipalib import api

ipaserver/advise/plugins/smart_card_auth.py

@@ -2,6 +2,8 @@
 # Copyright (C) 2017 FreeIPA Contributors see COPYING for license
 #
 
+from __future__ import absolute_import
+
 from ipalib.plugable import Registry
 from ipaplatform import services
 from ipaplatform.paths import paths