Add attributes "data-display" to clients table row

In clients table, row attribute "data-display" is missing, so
when we cann't see client name in deleting confirm dialog.
Now I fix it.

Change-Id: Ie0b6b7dcf419b1c4ab4b83715410b7bb678f39fe
Closes-bug: #1703501

disaster_recovery/clients/tables.py

@@ -66,7 +66,10 @@ class ClientsTable(tables.DataTable):
                               link=get_link)
     name = tables.Column('hostname', verbose_name=_("Hostname"))
 
-    class Meta:
+    def get_object_display_key(self, datum):
+        return "hostname"
+
+    class Meta(object):
         name = "clients"
         verbose_name = _("Clients")
         row_actions = (DeleteClient,)