Add circleci badge

Author: fpietka

README.md

@@ -1,4 +1,4 @@
-[![Build Status](https://scrutinizer-ci.com/g/fpietka/Zend-Nested-Set/badges/build.png?b=master)](https://scrutinizer-ci.com/g/fpietka/Zend-Nested-Set/build-status/master) [![Code Coverage](https://scrutinizer-ci.com/g/fpietka/Zend-Nested-Set/badges/coverage.png?b=master)](https://scrutinizer-ci.com/g/fpietka/Zend-Nested-Set/?branch=master) [![Scrutinizer Code Quality](https://scrutinizer-ci.com/g/fpietka/Zend-Nested-Set/badges/quality-score.png?b=master)](https://scrutinizer-ci.com/g/fpietka/Zend-Nested-Set/?branch=master)
+[![Build Status](https://scrutinizer-ci.com/g/fpietka/Zend-Nested-Set/badges/build.png?b=master)](https://scrutinizer-ci.com/g/fpietka/Zend-Nested-Set/build-status/master) [![Code Coverage](https://scrutinizer-ci.com/g/fpietka/Zend-Nested-Set/badges/coverage.png?b=master)](https://scrutinizer-ci.com/g/fpietka/Zend-Nested-Set/?branch=master) [![Scrutinizer Code Quality](https://scrutinizer-ci.com/g/fpietka/Zend-Nested-Set/badges/quality-score.png?b=master)](https://scrutinizer-ci.com/g/fpietka/Zend-Nested-Set/?branch=master) [![StyleCI](https://styleci.io/repos/452790/shield)](https://styleci.io/repos/452790)
 
 INSTALLATION
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