Merge pull request #50 from gitter-badger/gitter-badge

Add a Gitter chat badge to README.md

README.md

 # Element [![Build Status](https://travis-ci.org/ElemeFE/element.svg?branch=master)](https://travis-ci.org/ElemeFE/element) [![npm package](https://img.shields.io/npm/v/element-ui.svg)](https://www.npmjs.org/package/element-ui) [![NPM downloads](http://img.shields.io/npm/dm/element-ui.svg)](https://npmjs.org/package/element-ui)
+
+[![Join the chat at https://gitter.im/ElemeFE/element](https://badges.gitter.im/ElemeFE/element.svg)](https://gitter.im/ElemeFE/element?utm_source=badge&utm_medium=badge&utm_campaign=pr-badge&utm_content=badge)
 > Desktop UI elements for Vue.js 2.0.
 
 ## Docs