Permits a list of values for the "type=" tests attribute
Permits a list of values for the "type=" tests attribute

The changes to the decorator simply call testtools.testcase.attr
multiple times in case type= is a list. Retains compatibility with
testr too.

Change-Id: I3d850b10f7cb8b7df69df3e583698c3d4f25bdbc
Implements: blueprint convert-attr-to-testtools

cneill/tempest-lib,afaheem88/tempest-lib,mtreinish/tempest-lib,JioCloud/tempest-lib,varunarya10/tempest-lib,sorenh/tempest-lib