In Travis config, install nose-cov instead of nose-cover3

Author: Scott Torborg

.travis.yml

@@ -4,7 +4,7 @@ python:
   - "2.7"
 
 install:
-  - "pip install coverage nose-cover3 flake8 python-coveralls --use-mirrors"
+  - "pip install coverage nose-cov flake8 python-coveralls --use-mirrors"
   - "pip install -e . --use-mirrors"
 
 before_script: "flake8"