added travis build status to readme file

README.md

@@ -1,3 +1,5 @@
+[![Build Status](https://travis-ci.org/isarvalley/craftbeerpi3.svg?branch=core_refactoring)](https://travis-ci.org/isarvalley/craftbeerpi3)
+
 [![codebeat badge](https://codebeat.co/badges/72fa1981-c82a-488f-9a53-9e21ed9de4cc)](https://codebeat.co/projects/github-com-isarvalley-craftbeerpi3-core_refactoring)
 
 [![Codacy Badge](https://api.codacy.com/project/badge/Grade/0a970c7873f84953bd772c36d5ffc05c)](https://www.codacy.com/app/isar_valley/craftbeerpi3?utm_source=github.com&utm_medium=referral&utm_content=isarvalley/craftbeerpi3&utm_campaign=Badge_Grade)