withoutresponses is not a registered marker

[Markus Zapke-Gründemann]

Running pytest and pytest-responses with the --strict option fails, because "withoutresponses" is not a registered marker. This can be demonstrated with pytest-responses own test suite:

$ py.test --strict .
=================================================================== test session starts ====================================================================
platform darwin -- Python 3.5.1, pytest-2.9.2, py-1.4.34, pluggy-0.3.1
rootdir: /Users/keimlink/projects/pytest-responses, inifile: setup.cfg
plugins: responses-0.1.0
collected 0 items / 1 errors

========================================================================== ERRORS ==========================================================================
________________________________________________________ ERROR collecting test_pytest_responses.py _________________________________________________________
test_pytest_responses.py:14: in <module>
    @pytest.mark.withoutresponses
../../.virtualenvs/pytest-responses/lib/python3.5/site-packages/_pytest/mark.py:184: in __getattr__
    self._check(name)
../../.virtualenvs/pytest-responses/lib/python3.5/site-packages/_pytest/mark.py:199: in _check
    raise AttributeError("%r not a registered marker" % (name,))
E   AttributeError: 'withoutresponses' not a registered marker
================================================================= 1 error in 0.02 seconds ==================================================================