refactor: Store domains separately from users

templates/home.html

@@ -8,7 +8,7 @@
 	</div>
 	{% if other_users %}
 		<div>
-			<h2>Other users you have permission to see</h2>
+			<h2>Other users you have permission to see on your own domain</h2>
 			<ul>
 				{% for user in other_users %}
 					<li>{{ user.mail }}</li>