fixes travis config

Author: saxix

.travis.yml

@@ -48,7 +48,7 @@ install:
   - pip install tox coverage python-coveralls>=2.5 coveralls>=0.5 codecov
 
 script:
-  - tox -e $TOXENV -- tests -vv --capture=no --cov=concurrency \
+  - tox -e $TOXENV -- py.test tests -v --capture=no --cov=concurrency \
     --cov-report=xml --cov-config=tests/.coveragerc
 
 before_success: