pytest-django-9999.ebuild: Add a 'test' flag to IUSE

This doesn't work, and I'm even having problems with 'make test' in a
fresh checkout:

   ERROR collecting lib64/python3.3/site-packages/setuptools/tests/test_egg_info.py
  lib64/python3.3/site-packages/setuptools/tests/test_egg_info.py:9: in <module>
      ENTRIES_V10 = pkg_resources.resource_string(__name__, 'entries-v10')
  lib/python3.3/site-packages/pkg_resources.py:957: in resource_string
      self, resource_name
  lib/python3.3/site-packages/pkg_resources.py:1409: in get_resource_string
      return self._get(self._fn(self.module_path, resource_name))
  lib/python3.3/site-packages/pkg_resources.py:1536: in _get
      stream = open(path, 'rb')
  E   FileNotFoundError: [Errno 2] No such file or directory: '/.../pytest-django/lib64/python3.3/site-packages/setuptools/tests/entries-v10'
  ________ ERROR at setup of ModelBackendTest.test_authentication_timing _________

  request = <SubRequest '_django_setup_unittest' for <TestCaseFunction 'test_authentication_timing'>>
  _django_cursor_wrapper = <pytest_django.plugin.CursorManager object at 0x7fe5cf24e110>

      @pytest.fixture(autouse=True)
      def _django_setup_unittest(request, _django_cursor_wrapper):
          """Setup a django unittest, internal to pytest-django"""
          if django_settings_is_configured() and is_django_unittest(request.node):
              request.getfuncargvalue('_django_test_environment')
  >           request.getfuncargvalue('_django_db_setup')

  pytest_django/plugin.py:273:

And on and on.  'make test >/tmp/test 2>&1' dropped 273 MB of errors
into /tmp/test ;).

dev-python/pytest-django-9999.ebuild: Add this Raven test dependency

I haven't been able to get the test suite working locally, so I'm
leaving it out of this commit.