Update README badges

Added an `ember-version` badge, inspired by the one on `ember-concurrency`

README.md

@@ -1,4 +1,9 @@
-# ember-ajax [![Travis CI Build Status](https://travis-ci.org/ember-cli/ember-ajax.svg?branch=master)](https://travis-ci.org/ember-cli/ember-ajax) [![AppVeyor Build status](https://ci.appveyor.com/api/projects/status/rjfngst9s19p3cp8/branch/master?svg=true)](https://ci.appveyor.com/project/alexlafroscia/ember-ajax/branch/master) [![Ember Observer Score](http://emberobserver.com/badges/ember-ajax.svg)](http://emberobserver.com/addons/ember-ajax)
+# ember-ajax
+
+[![Travis CI Build Status](https://travis-ci.org/ember-cli/ember-ajax.svg?branch=master)](https://travis-ci.org/ember-cli/ember-ajax)
+[![AppVeyor Build status](https://ci.appveyor.com/api/projects/status/rjfngst9s19p3cp8/branch/master?svg=true)](https://ci.appveyor.com/project/alexlafroscia/ember-ajax/branch/master)
+[![Ember Observer Score](http://emberobserver.com/badges/ember-ajax.svg)](http://emberobserver.com/addons/ember-ajax)
+![Ember Version][ember-version]
 
 Service for making AJAX requests in Ember 1.13+ applications.
 
@@ -469,3 +474,5 @@ Ajax requests.
 ## Special Thanks
 
 This addon was based on ajax handing in Ember Data's Adapter.
+
+[ember-version]: https://embadge.io/v1/badge.svg?start=1.13.0