[SEBA-450] (part 2)

Add tox testing support on additional XOS library modules:

- xos-api
- xos-kafka (has no tests)
- xos-migrate (has no tests)
- xos-synchronizer

Change-Id: I98195bc9747971d3515882d517affe058dd86ac5
diff --git a/lib/xos-synchronizer/xos-synchronizer-tests/test_event_steps/event_step.py b/lib/xos-synchronizer/xos-synchronizer-tests/test_event_steps/event_step.py
index 372d6d3..77402ba 100644
--- a/lib/xos-synchronizer/xos-synchronizer-tests/test_event_steps/event_step.py
+++ b/lib/xos-synchronizer/xos-synchronizer-tests/test_event_steps/event_step.py
@@ -13,6 +13,7 @@
 # limitations under the License.
 
 from __future__ import print_function
+from __future__ import absolute_import
 from xossynchronizer.event_steps.eventstep import EventStep
 from mock_modelaccessor import *