Rework oz.git unittests

Greetings, I've been looking into integrating existing oz unittests with jenkins. It wasn't hard to have them run in jenkins as is, but I was looking give jenkins a better idea for pass/fail data over time. One way to do this was to convert the tests to use py.test (or unittest -- but that's a little crusty). Py.test can emit junit XML test output, which is jenkins friendly, and has much less stock test class/method bloat. I've modified the existing oz unittests to be py.test friendly. Another annoyance with running tests in jenkins is that the nodes need to be manually setup with appropriate dependencies ahead of time. While this isn't hard, it's maintenance and one more thing to forget/fail when testing. The new test driver (runtests.sh) will setup a python virtualenv and install required dependencies there. This is intended to handle deps installation during unittest execution. Comments appreciated. Thanks, James