chore(): Added travis badge to README.

Author: hansl

README.md

@@ -1,5 +1,7 @@
 # Material Design for Angular 2
 
+[![Build Status](https://travis-ci.org/angular/material2.svg?branch=master)](https://travis-ci.org/angular/material2)
+
 This is the home for the Angular team's Material Design components built on top of Angular 2.
 Things are in very early stages now- check back soon for more progress.