Add Pledgie (by request)

Author: ryanstout

Readme.md

@@ -1,6 +1,7 @@
 [![Gem Version](https://badge.fury.io/rb/volt.png)](http://badge.fury.io/rb/volt)
 [![Code Climate](https://codeclimate.com/github/voltrb/volt.png)](https://codeclimate.com/github/voltrb/volt)
 [![Build Status](https://travis-ci.org/voltrb/volt.png?branch=master)](https://travis-ci.org/voltrb/volt)
+[https://pledgie.com/campaigns/26731.png?skin_name=chrome](https://pledgie.com/campaigns/26731)
 
 # Volt