Fix: search header attribute escaping

Broken in my previous commit, d6f4aaa. This causes attributes to be
doubly escaped. For example,
http://localhost:8181/wiki/Main_Page?uselang=he.

Change-Id: I9776a3c355081dc5fec7753edf256f55dfe6045b

includes/templates/SearchComponent.mustache

@@ -1,5 +1,5 @@
 <div id="p-search" role="search">
-	<h3 {{searchHeaderAttrs}}>
+	<h3 {{{searchHeaderAttrs}}}>
 		<label for="searchInput">{{searchInputLabel}}</label>
 	</h3>
 	<form action="{{searchAction}}" id="searchform">