Another try at progress events.

Now asyncs send the progress by calling
this.sendProgress(current, min, max, [optional sourceEvent]);

The resulting event contains current,min and max properties. The optional source event is merged into the event.

Enyo-DCO-1-1-Signed-Off-By: Jascha Dachtera (jascha.dachtera@gmail.com)
Merge remote-tracking branch 'origin/async-progress' into async-progress

Conflicts:
	source/ajax/Async.js
Another try at progress events.

Now asyncs send the progress by calling
this.sendProgress(current, min, max, [optional sourceEvent]);

The resulting event contains current,min and max properties. The optional source event is merged into the event.

Enyo-DCO-1-1-Signed-Off-By: Jascha Dachtera (jascha.dachtera@gmail.com)