Merge pull request #2935 from Raven24/host-meta

adapt host-meta document to RFC 6415

app/views/publics/host_meta.erb

 <?xml version='1.0' encoding='UTF-8'?>
-<XRD xmlns='http://docs.oasis-open.org/ns/xri/xrd-1.0'
-     xmlns:hm='http://host-meta.net/xrd/1.0'>
-     <hm:Host><%= AppConfig[:pod_bare_domain] %></hm:Host>
+<XRD xmlns='http://docs.oasis-open.org/ns/xri/xrd-1.0'>
+
+  <!-- Resource-specific Information -->
+
   <Link rel='lrdd'
-        template='<%= AppConfig[:pod_url] %>webfinger?q={uri}'>
-    <Title>Resource Descriptor</Title>
-  </Link>
+        type='application/xrd+xml'
+        template='<%= AppConfig[:pod_url] %>webfinger?q={uri}' />
+
 </XRD>