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>

ipatests/test_cmdline/test_ipagetkeytab.py

@@ -20,6 +20,8 @@
 Test `ipa-getkeytab`
 """
 
+from __future__ import absolute_import
+
 import os
 import shutil
 import tempfile