[TIMOB-1910] Add a removeAllChildren method to views and windows

   var win = Ti.UI.createWindow({
   	backgroundColor:'black'
   });
   for (var i=0; i < 10; i++) {
   	var x = i * 20;
   	for (var j=0; j < 20; j++) {
   		var y = j * 20;
   		var color = 'red';
   		switch ((x+y) % 3) {
   			case 1:
   				color = 'green';
   				break;
   			case 2:
   				color = 'blue';
   				break;
   			default:
   				color = 'red';
   				break;
   		}
   		var view = Ti.UI.createView({
   			left:x,
   			top:y,
   			width:20,
   			height:20,
   			backgroundColor:color
   		});
   		win.add(view);
   	}
   }
   
   var b = Ti.UI.createButton({
   	title:'Clear the view!',
   	width:200,
   	height:40
   });
   win.add(b);
   b.addEventListener('click', function() {
   	var viewChildren = win.children;
   	Ti.API.info(viewChildren);
   	for (var i=0; i < viewChildren.length; i++) {
   		var child = viewChildren[i];
   		win.remove(child);	
   	}
   });
   win.open();