Job #19612 - Add New Scripting Features to Interface

For worklist job: https://worklist.net/19612

Notes from job:

> * Add a "window" global variable/object to JS in Interface.
> * Expose the following JS standard methods to this object (see 
> * window.location - note: this should return the hifi formatted URL of the current location. It should also support setting this.
> * window.alert("sometext");
> * window.confirm("sometext");
> * window.prompt("sometext","defaultText");
> * window.innerHeight
> * window.innerWidth
> 
> For more details on these properties see:
> * https://developer.mozilla.org/en-US/docs/Web/API/Window
> * http://www.w3schools.com/js/js_popup.asp
> * http://www.w3schools.com/js/js_window_location.asp
> * https://developer.mozilla.org/en-US/docs/Web/API/Window.location
> 
> Some extra notes on location...
> * In the case of Location, the location.protocol will always be "hifi://" 
> 
> Note: As will standard browsers, the location object should be available globally and/or as a member of window.