mod_s2s_keepalive: Fix response handler (thanks Ge0rG) So there are no 'iq-{result,error}/host' events, mod_iq only fires events for result stanzas that include the full 'id' attr. This fixes it by hooking the stanza router event.

<tr>
  <th>What is {x} {op} {y}?</th><td>
    <input name="captcha_challenge" type="hidden" value="{challenge}">
    <input name="captcha_reply" pattern="[0-9]+" required type="number">
  </td></tr>