Add travis build badge

Author: SpaiR

README.md

@@ -1,5 +1,6 @@
 # imgui-java
 
+[![Build Status](https://travis-ci.org/SpaiR/imgui-java.svg?branch=master)](https://travis-ci.org/SpaiR/imgui-java)
 [![JCenter](https://img.shields.io/bintray/v/spair/io.imgui.java/binding.svg?label=binding)](https://bintray.com/spair/io.imgui.java/binding/_latestVersion)
 [![JCenter](https://img.shields.io/bintray/v/spair/io.imgui.java/lwjgl3.svg?label=lwjgl3)](https://bintray.com/spair/io.imgui.java/lwjgl3/_latestVersion)
 [![javadoc](https://javadoc.io/badge2/io.imgui.java/binding/javadoc.svg)](https://javadoc.io/doc/io.imgui.java/binding)