Tests do not run using 'python setup.py test'

Tests run fine using the command

```
    py.test glue
```

However, if trying with either

```
    ./runtests.py
    python setup.py test
```

one will be greeted with a stack trace similar to the below.

```
    (glue)[user glue-repo]$ python setup.py test
    running test
    INTERNALERROR> Traceback (most recent call last):
    INTERNALERROR>   File "_pytest.main", line 68, in wrap_session
    INTERNALERROR>     config.pluginmanager.do_configure(config)
    INTERNALERROR>   File "_pytest.core", line 267, in do_configure
    INTERNALERROR>     config.hook.pytest_configure(config=self._config)
    INTERNALERROR>   File "_pytest.core", line 419, in __call__
    INTERNALERROR>     return self._docall(methods, kwargs)
    INTERNALERROR>   File "_pytest.core", line 430, in _docall
    INTERNALERROR>     res = mc.execute()
    INTERNALERROR>   File "_pytest.core", line 348, in execute
    INTERNALERROR>     res = method(**kwargs)
    INTERNALERROR>   File "/Users/eisenham/Documents/ssbdev/play/glue/glue-repo/glue/conftest.py", line 7, in pytest_configure
    INTERNALERROR>     if config.getoption('no_optional_skip'):
    INTERNALERROR> AttributeError: 'Config' object has no attribute 'getoption'
```