[fix] Remove --source from coverage in .travis.yml

Author: nwtgck

.travis.yml

@@ -24,7 +24,7 @@ install:
   - pip install coveralls
 
 script:
-  - coverage run --source=nwtgck_hello_test setup.py test
+  - coverage run setup.py test
 
 after_success:
   - coveralls