global: InvenioTestCase in test suite
global: InvenioTestCase in test suite

* Introduces InvenioTestCase class that is to be used in all test
  suits instead of standard unittest.TestCase class.  Facilitates
  later merging to next.

Signed-off-by: Tibor Simko <c7116e45300b163846dc01f3ed02116e3f8ef7a5@cern.ch>

inveniosoftware/invenio-base,tiborsimko/invenio-base,tiborsimko/invenio-base,inveniosoftware/invenio-base