Update .travis.yml

.travis.yml

@@ -13,6 +13,8 @@ install:
   - "sudo apt-get install -y mongodb-org" 
   - "sudo service mongod start"
   - "python setup.py -q install"
-  - "pip install pytest-pep8"
+  - "pip install pytest-pep8 pytest-cov codecov"
 # command to run tests
-script: pytest
+script: "pytest --cov=./"
+after_success:
+- codecov