Added Gitter badge

README.md

@@ -1,4 +1,6 @@
 # <img alt="NodeBB" src="http://i.imgur.com/mYxPPtB.png" />
+
+[![Gitter](https://badges.gitter.im/Join%20Chat.svg)](https://gitter.im/NodeBB/NodeBB?utm_source=badge&utm_medium=badge&utm_campaign=pr-badge&utm_content=badge)
 [![Build Status](https://travis-ci.org/NodeBB/NodeBB.svg?branch=master)](https://travis-ci.org/NodeBB/NodeBB)
 [![Dependency Status](https://david-dm.org/nodebb/nodebb.svg)](https://david-dm.org/nodebb/nodebb)
 [![Code Climate](https://codeclimate.com/github/NodeBB/NodeBB/badges/gpa.svg)](https://codeclimate.com/github/NodeBB/NodeBB)