adding travis image to readme

README.md

@@ -1,3 +1,5 @@
+[![Build Status](https://travis-ci.org/jhonnymertz/java-wkhtmltopdf-wrapper.svg?branch=master)](https://travis-ci.org/jhonnymertz/java-wkhtmltopdf-wrapper)
+
 Java WkHtmlToPdf Wrapper
 =========