Improve automatic emails with temporary urls

This MR targets the improvement for automatic emails concerning validation of new users by supervisors/re-validation of users.

Fixes #542 (closed)

Fixes #550 (closed)

beat/web/accounts/templates/accounts/url_validation_failed.html

@@ -55,7 +55,7 @@
 <div class="row">
   <div class="col-sm-6 col-sm-offset-3">
     {% with 48 as width %}
-	<h3 class="page-title"><img class="img-circle" width="{{ width }}" height="{{ width }}" data-toggle="tooltip" data-placement="top" title="To change your avatar, visit http://gravatar.com"></img>You can't validate this supervisee</h3>
+	<h3 class="page-title"><img class="img-circle" width="{{ width }}" height="{{ width }}" data-toggle="tooltip" data-placement="top" title="To change your avatar, visit http://gravatar.com"></img>You can't validate this supervisee!</h3>
     {% endwith %}
   </div>
 </div>