Don't use tox-travis anymore

Author: chdemko

.travis.yml

@@ -9,7 +9,7 @@ before_install:
   - pip install --user --upgrade pip
 install:
   - pip install --user coveralls
-  - pip install --user tox-travis
+  - pip install --user tox
 script:
   - tox
   - coverage report -m