Set cache to "pip"

Author: dzwarg

.travis.yml

@@ -3,6 +3,8 @@ python:
   - "2.7"
 before_install:
   - sudo apt-get -y install libxml2-dev libxslt-dev python-dev
+cache:
+  pip: true
 # command to install dependencies
 install:
   - pip install -r requirements.txt