Add option to show browser's local time (#1653)

* Add tests for --local-time option
* Update Readme

lib/gollum/templates/layout.mustache

@@ -14,6 +14,7 @@
   <script>
   var criticMarkup = '{{critic_markup}}';
 	var baseUrl = '{{base_url}}';
+  var showLocalTime = {{{show_local_time}}};
 	var uploadDest = 'uploads';
 	var perPageUploads = '{{per_page_uploads}}';
 	if (perPageUploads == 'true') {