Fix namespaces used when returning stream errors.
Fix namespaces used when returning stream errors.

Previously, <stream:error> stanzas coming from the XMPP server would be
sent to connected clients with mangled namespaces, like so:

  <body xmlns='http://jabber.org/protocol/httpbind' type='terminate'
    condition='remote-stream-error'>
    <ns0:error xmlns:ns0='http://etherx.jabber.org/streams'>
      <system-shutdown xmlns='urn:ietf:params:xml:ns:xmpp-streams'/>
    </ns0:error>
  </body>

Now they will have correct prefixes:

  <body xmlns='http://jabber.org/protocol/httpbind' type='terminate'
    condition='remote-stream-error'>
    <stream:error xmlns:stream='http://etherx.jabber.org/streams'>
      <system-shutdown xmlns='urn:ietf:params:xml:ns:xmpp-streams'/>
    </stream:error>
  </body>

twonds/punjab,twonds/punjab,twonds/punjab