Change Travis configuration to include subdirectories under examples

Author: dcbriccetti

.travis.yml

@@ -27,6 +27,6 @@ install:
 
 script:
   - pylint adafruit_circuitplayground/*.py
-  - ([[ ! -d "examples" ]] || pylint --disable=missing-docstring,invalid-name examples/*.py)
+  - ([[ ! -d "examples" ]] || pylint --disable=missing-docstring,invalid-name `find ./examples -name "*.py"`)
   - circuitpython-build-bundles --filename_prefix adafruit-circuitpython-circuitplayground --library_location .
   - cd docs && sphinx-build -E -W -b html . _build/html