Added tox to requirements

Author: Nurdok

requirements/tests.txt

@@ -1,3 +1,4 @@
 pytest==2.7.3
 pytest-pep8
-mock
+mock
+tox

src/tests/test_integration.py

@@ -112,6 +112,7 @@ def env(request):
     with TestEnv(request.param) as test_env:
         yield test_env
 
+
 pytestmark = pytest.mark.usefixtures("install_package")