Before this patch all ERP5 SlapOS Integration tests only run with ZEO
storage. We should also run them against NEO, because we are using
ERP5 with NEO in SlapOS.

Because we are testing WCFS against NEO now, we need compatible
NEO => WCFS and ZODB => WCFS versions for successful tests. This is
the reason why we need to add a specific 'test.cfg' here, which
ensures compatible versions are installed.

For tests which shouldn't be split into NEO/ZEO flavoured test cases,
this patch adds the '__parameterized__' class attribute, which can
be set to 'False' (default to 'True').