some live-test-runner cleanups: stop bloating sys.path at every run, stop assuming test names are test modules (allows specifying testPackingList.TestPackingList in the test list), stop monkeypatching classes

git-svn-id: https://svn.erp5.org/repos/public/erp5/trunk@44198 20353a03-c40f-0410-a6d1-a30d3c3de9de