Removed gitter link

Almost no one was using the gitter room for this repo, so we've deleted it.

Author: kwalrath

README.md

@@ -1,7 +1,6 @@
 # The webdev site
 
 [![Build Status](https://travis-ci.org/dart-lang/site-webdev.svg?branch=master)](https://travis-ci.org/dart-lang/site-webdev)
-[![Join the chat at https://gitter.im/dart-lang/site-webdev](https://badges.gitter.im/Join%20Chat.svg)](https://gitter.im/dart-lang/site-webdev?utm_source=badge&utm_medium=badge&utm_campaign=pr-badge&utm_content=badge)
 
 This repo implements the [webdev.dartlang.org](http://webdev.dartlang.org) website. It uses the tools and infrastructure of
 www.dartlang.org (which is implemented in [github.com/dart-lang/site-www](https://github.com/dart-lang/site-www)).