AS7-6854 Enable CORS Requests

We've been prototyping an alternative distribution channel for the console: You can retrieve a standalone version of the console through a static URL like the mozilla marketplace (chrome web store would be another alternative) and connect to any domain controller, wether it runs locally or remotely.

To make this happen the AS instance needs to support [CORS](http://en.wikipedia.org/wiki/Cross-origin_resource_sharing). 

Related issue: https://issues.jboss.org/browse/AS7-6854