Enable pip cache in Travis CI (#305)

jdufresne · sigmavirus24 · commit d004fbdc1f02 · 2017-10-21T17:46:10.000-05:00
Can speed up builds and reduce load on PyPI servers. For more information, see: https://docs.travis-ci.com/user/caching/#pip-cache
diff --git a/.travis.yml b/.travis.yml
@@ -1,4 +1,5 @@
 language: python
+cache: pip
 python:
   - 2.6
   - 2.7
