travis config: use nose instead of py.test

Author: manu-chroma

.travis.yml

@@ -4,6 +4,6 @@ python:
   - "3.4"
   - "3.5"
 #  - "3.6"
-#install:
-#   - pip install .
-script: py.test
+install:
+   - pip install .
+script: nosetests