Adding CodeClimate badge.

README.md

@@ -3,6 +3,7 @@
 [![Build Status](https://scrutinizer-ci.com/g/allebb/cartographer/badges/build.png?b=master)](https://scrutinizer-ci.com/g/allebb/cartographer/build-status/master)
 [![Code Coverage](https://scrutinizer-ci.com/g/allebb/cartographer/badges/coverage.png?b=master)](https://scrutinizer-ci.com/g/allebb/cartographer/?branch=master)
 [![Scrutinizer Code Quality](https://scrutinizer-ci.com/g/allebb/cartographer/badges/quality-score.png?b=master)](https://scrutinizer-ci.com/g/allebb/cartographer/?branch=master)
+[![Code Climate](https://codeclimate.com/github/allebb/cartographer/badges/gpa.svg)](https://codeclimate.com/github/allebb/cartographer)
 [![Latest Stable Version](https://poser.pugx.org/ballen/cartographer/v/stable)](https://packagist.org/packages/ballen/cartographer)
 [![Latest Unstable Version](https://poser.pugx.org/ballen/cartographer/v/unstable)](https://packagist.org/packages/ballen/cartographer)
 [![License](https://poser.pugx.org/ballen/cartographer/license)](https://packagist.org/packages/ballen/cartographer)