Thanks to Thibaut Frain for this patch.

Display the error in the console.

The method .on, .off, .trigger have been added.
See RSVP.EventTarget.mixin for full details.

Propagate the events in case of EmbeddedGadget to the parent IframeGadget.

As renderJS is not compatible with phantomJS (which does not support CSS
loading events), no need to slow down default execution.

Drop jQuery usage in test.

Replace jQuery by RSVP.
Allow to declareGadget without attaching it to the DOM.
Correctly handle error.

IFrame are currently broken.

Thanks to Caleb James DeLisle.

A better fix in this case would be to cleanly allow RenderJS gadget
instanciation to wait for some events (require and any other JS code)
before deciding that a gadget is ready. Currently, RenderJS ready
function is triggered when all JS scripts defined in the HTML page are
loaded. One idea would be to extend the API to allow the gadget to
explicitely trigger the ready callback (but it will block the full
system if one gadget failed to load).

Thanks to Caleb James DeLisle.

It only works inside an iframed gadget.