update readme with travis badge

README.md

@@ -1,6 +1,8 @@
 # grunt-injector
 
-# HELP WANTED!
+[![Build Status](https://api.travis-ci.org/klei/grunt-injector.svg?branch=master)](https://travis-ci.org/klei/grunt-injector)
+
+# Contributors are welcomed!
 
 **I don't have enough time to maintain this plugin as I would want to, so I'm looking for people who want to help out and be contributors/repository admins.**