Add maintenance announcement tag helper

Change-Id: Ie4a18bf28e38613f9f2faded9c84be023f517b34
diff --git a/templates/partial/maintenance.html.ep b/templates/partial/maintenance.html.ep
new file mode 100644
index 0000000..39b9f50
--- /dev/null
+++ b/templates/partial/maintenance.html.ep
@@ -0,0 +1,5 @@
+  <dt class="maintenance"><time datetime="<%= $dt->ymd %>"><%= $dt->day_name %>, <%= loc('numo', day => $dt->day) %> <%= $dt->month_name %> <%= $dt->year %></time></dt>
+  <dd  class="maintenance">
+    <h4><%= loc 'maintenanceWork_time' %> <%= $start_time %> - <%= $end_time %> <%= loc('oclock') %></h4>
+    <p><%= loc 'maintenanceWork_desc' %></p>
+  </dd>