added image for "head on",

removed unneeded images

WebContent/main.js

@@ -71,6 +71,7 @@ OSRM.prefetchImages = function() {
 		              	{id:'direction_6',						url:'images/slight-left.png'},
 		              	{id:'direction_7',						url:'images/turn-left.png'},
 		              	{id:'direction_8',						url:'images/sharp-left.png'},
+		              	{id:'direction_10',						url:'images/head.png'},
 		        		{id:'direction_11',						url:'images/round-about.png'},
 		        		{id:'direction_15',						url:'images/target.png'}
 	               ];