Add Scrutinizer quality score [skip ci]

Author: matthiasnoback

README.md

@@ -4,6 +4,8 @@ By Matthias Noback
 
 [![Build Status](https://secure.travis-ci.org/matthiasnoback/symfony-service-definition-validator.png)](http://travis-ci.org/matthiasnoback/symfony-service-definition-validator)
 
+[![Scrutinizer Quality Score](https://scrutinizer-ci.com/g/matthiasnoback/symfony-service-definition-validator/badges/quality-score.png?s=c04fb4a34fa5d4c27f1e4ef0d8794c07b3c40e91)](https://scrutinizer-ci.com/g/matthiasnoback/symfony-service-definition-validator/)
+
 ## Installation
 
 Using Composer: