Execute doctest in Travis

.travis.yml

@@ -27,7 +27,7 @@ script:
   - export NO_GPU_EXECUTION=1
   - pip install -e .
   - if [[ "$LINT" == "false" ]]; then python setup.py test; fi
-  - if [[ "$LINT" == "true" ]]; then flake8 src; fi
+  - if [[ "$LINT" == "true" ]]; then flake8 src;python setup.py doctest; fi
 after_success:
   - if [[ "$COVERAGE" == "true" ]]; then coveralls || echo "failed"; codecov; fi
 after_script: