Modify and propagate changed lease.

If hostname is reset on existing lease, propagate such change to leases
file and script.

src/lease.c

@@ -1021,6 +1021,7 @@ void lease_set_hostname(struct dhcp_lease *lease, const char *name, int auth, ch
 	    }
 	
 	  kill_name(lease_tmp);
+	  lease_tmp->flags |= LEASE_CHANGED; /* run script on change */
 	  break;
 	}
     }