Clean up tenants created in test_users.py

Test_list_user_projects in test_users.py creates a tenant but
the tenant is not deleted at the end of the test.
This patch makes the tenant be deleted by adding addCleanup.

Fixes bug: 1179739

Change-Id: Ifc361363f74dcc43286e5fbdb582adf7f452dacc
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
Merge "Permits a list of values for the "type=" tests attribute"