Merge pull request #80 from gitter-badger/gitter-badge

Add a Gitter chat badge to README.md

Author: mpeterv

README.md

@@ -1,5 +1,7 @@
 # Luacheck
 
+[![Join the chat at https://gitter.im/luacheck/Lobby](https://badges.gitter.im/luacheck/Lobby.svg)](https://gitter.im/luacheck/Lobby?utm_source=badge&utm_medium=badge&utm_campaign=pr-badge&utm_content=badge)
+
 [![Build Status](https://travis-ci.org/mpeterv/luacheck.png?branch=master)](https://travis-ci.org/mpeterv/luacheck)
 [![Windows build status](https://ci.appveyor.com/api/projects/status/pgox2vvelagw1fux/branch/master?svg=true&passingText=Windows%20build%20passing&failingText=Windows%20build%20failing)](https://ci.appveyor.com/project/mpeterv/luacheck/branch/master)
 [![Coverage Status](https://coveralls.io/repos/mpeterv/luacheck/badge.svg?branch=master)](https://coveralls.io/r/mpeterv/luacheck?branch=master)