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.

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').