Add support for adding Java event handlers to JavaScript in the WebView based browser component

I'm using the recommended way of creating a _JavaScript -> Java_ integration as described in the [_Calling back to Java from JavaScript_ section of the WebEngine JavaDoc](http://docs.oracle.com/javafx/2/api/javafx/scene/web/WebEngine.html)

I've also put the test in the _soapui-system-test_ module since it's time dependent and more of a integration test


_SOAP-2329_