Add further py.test arguments to setup.py
Enable junitxml under testreports.dir
Move unit tests to OmeroPy/test/unit
Refactor PyTest out to tools/test_setup.py

OmeroFS and all other python-based tools components will
need the PyTest class as a command in their setup.py.
Migrate clitests to PyTest
Migrate cmdtest to PyTest
Migrate tablestest/setup.py to PyTest
Migrate tablestest.integration_suite to PyTest
Migrate scriptstest/suite.py to PyTest
Migrate scriptstest/integration_suite.py to PyTest
Migrate PythonOnly to PyTest
Remove integration_suite.py
Fix unit test execution