registerWithAttributes

Add attributes parameter for additional registration info (for example: email). 

XEP-0077: In-Band Registration
Ref: http://xmpp.org/extensions/xep-0077.html

<iq type='set' id='reg2'>
  <query xmlns='jabber:iq:register'>
    <username>bill</username>
    <password>Calliope</password>
    <email>bard@shakespeare.lit</email>
  </query>
</iq>