Extend build commands to run doctests

Author: txels

.travis.yml

@@ -8,4 +8,5 @@ python:
 install: pip install -r test-requirements.txt
 script:
     - python -m unittest discover || python -m unittest
+    - python -m doctest abe/utils.py
     - flake8 abe tests

ep.yml

@@ -8,6 +8,7 @@ run:
   - coverage erase
   - coverage run --omit="*/tests/*","*$VIRTUAL_ENV*" -m unittest discover
   - coverage html
+  - python -m doctest abe/utils.py
 publish:
   - git diff --exit-code
   - ep run