configure coverage

.coveragerc

 [run]
 source = tracim
 omit = tracim/test*
+
+[report]
+omit =
+tests/*
+*/python?.?/*

.travis.yml

 install:
   - pip install --upgrade pip setuptools
   - pip install -e ".[testing]"
+  - pip install pytest-cov
+  - pip install python-coveralls
 
-script: pytest
+script:
+ - py.test --cov tracim
 
 after_success:
   - coveralls