added ability to add forum to iOS homescreen as an app

public/templates/header.tpl

@@ -5,6 +5,7 @@
 	<meta name="viewport" content="width=device-width, initial-scale=1.0">
 	<meta name="title" CONTENT="NodeBB">
 	<meta name="description" content="Node.js/Redis/Socket.io powered forums for a new generation">
+	<meta name="apple-mobile-web-app-capable" content="yes" />
 	<link href="{cssSrc}" rel="stylesheet" media="screen">
 	<link href="/vendor/bootstrap/css/bootstrap-responsive.min.css" rel="stylesheet" media="screen">
 	<link rel="stylesheet" href="/vendor/fontawesome/css/font-awesome.min.css">