Add label to icon symbolizer

https://github.com/openlayers/ol3/issues/886
		        new ol.style.Icon({
		        	url: 'http://127.0.0.1/console/img/officer.png',
		        	opacity: 1,
		        	width: 24,
		        	height: 24,
					label: new ol.style.Text({
					        	color: '#000',
					        	text: ol.expr.parse('i'),
					        	fontFamily: 'Calibri,sans-serif',
					        	fontSize: 10,
					        	textBaseline: 'top'
					        }),
					labelVAlign: 'bottom', //vertical align. not required [top|bottom]. default top
					labelAlign: 'center' //horizontal align. not required [left|right|center]. default center
		        })