Enhancement: Use SVG badge for Code Climate GPA

Author: localheinz

README.md

@@ -1,4 +1,5 @@
-[![Code Climate](https://codeclimate.com/github/codeclimate/php-test-reporter.png)](https://codeclimate.com/github/codeclimate/php-test-reporter) [![Build Status](https://travis-ci.org/codeclimate/php-test-reporter.svg?branch=master)](https://travis-ci.org/codeclimate/php-test-reporter)
+[![Code Climate](https://codeclimate.com/github/codeclimate/php-test-reporter.svg)](https://codeclimate.com/github/codeclimate/php-test-reporter) 
+[![Build Status](https://travis-ci.org/codeclimate/php-test-reporter.svg?branch=master)](https://travis-ci.org/codeclimate/php-test-reporter)
 
 # codeclimate-test-reporter