Favicons for mobile devices.

services/web/app/views/layout.pug

@@ -18,7 +18,10 @@ html(itemscope, itemtype='http://schema.org/Product')
 		-else
 			title= translate(title) + ' - ShareLaTeX, ' + translate("online_latex_editor") 
 
-		link(rel="icon", href="/favicon.ico")
+		link(rel="icon", href="favicon.ico")
+		link(rel="icon", sizes="192x192", href="touch-icon-192x192.png")
+		link(rel="apple-touch-icon-precomposed", href="favicon-152.png")
+			
 		link(rel='stylesheet', href=buildCssPath('/style.css'))
 
 		block _headLinks