Add code climate badge [ci skip]

Author: derrickreimer

README.md

@@ -3,6 +3,7 @@
 A Ruby toolkit for the [Drip](https://www.getdrip.com/) API.
 
 [![Build Status](https://travis-ci.org/DripEmail/drip-ruby.svg?branch=master)](https://travis-ci.org/DripEmail/drip-ruby)
+[![Code Climate](https://codeclimate.com/github/DripEmail/drip-ruby/badges/gpa.svg)](https://codeclimate.com/github/DripEmail/drip-ruby)
 
 ## Installation