Added gitter badge to readme.

README.md

@@ -1,5 +1,6 @@
 # zorg-gpio
 
+[![Join the chat at https://gitter.im/zorg/zorg](https://badges.gitter.im/Join%20Chat.svg)](https://gitter.im/zorg/zorg?utm_source=badge&utm_medium=badge&utm_campaign=pr-badge&utm_content=badge)
 [![Package Version](https://img.shields.io/pypi/v/zorg-gpio.svg)](https://pypi.python.org/pypi/zorg-gpio/)
 [![Requirements Status](https://requires.io/github/zorg/zorg-gpio/requirements.svg?branch=master)](https://requires.io/github/zorg/zorg-gpio/requirements/?branch=master)
 [![Build Status](https://travis-ci.org/zorg/zorg-gpio.svg?branch=master)](https://travis-ci.org/zorg/zorg-gpio)