mod_storage_xmlarchive: Fix return of numeric 'when' from key-value API At some point, 'when' was stored as a timestamp string then as a numeric UNIX timestamp, so both cases needs to be handled, as they are elsewhere. Thanks spec/core_storagemanager_spec.lua

<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>