Merge pull request #304 from tt/use-travis

Use Travis

.travis.yml

+sudo: false
+script: exit 0

Readme.md → README.md

-# Heroku Buildpack: Python
+# Heroku Buildpack: Python [![Build Status](https://travis-ci.org/heroku/heroku-buildpack-python.svg?branch=master)](https://travis-ci.org/heroku/heroku-buildpack-python)
 ![python](https://cloud.githubusercontent.com/assets/51578/13712821/b68a42ce-e793-11e5-96b0-d8eb978137ba.png)
 
 This is the official [Heroku buildpack](https://devcenter.heroku.com/articles/buildpacks) for Python apps, powered by [pip](https://pip.pypa.io/) and other excellent software.