Added Gitter badge.

Author: Roman Syroeshko

README.md

@@ -1,5 +1,7 @@
 # ![PHPWord](https://rawgit.com/PHPOffice/PHPWord/develop/docs/images/phpword.svg "PHPWord")
 
+[![Join the chat at https://gitter.im/PHPOffice/PHPWord](https://badges.gitter.im/Join%20Chat.svg)](https://gitter.im/PHPOffice/PHPWord?utm_source=badge&utm_medium=badge&utm_campaign=pr-badge&utm_content=badge)
+
 [![Latest Stable Version](https://poser.pugx.org/phpoffice/phpword/v/stable.png)](https://packagist.org/packages/phpoffice/phpword)
 [![Build Status](https://travis-ci.org/PHPOffice/PHPWord.svg?branch=master)](https://travis-ci.org/PHPOffice/PHPWord)
 [![Code Quality](https://scrutinizer-ci.com/g/PHPOffice/PHPWord/badges/quality-score.png?s=b5997ce59ac2816b4514f3a38de9900f6d492c1d)](https://scrutinizer-ci.com/g/PHPOffice/PHPWord/)