Do not link the guest account with any configured XMPP client (in

jabber.conf). The actual connection is made when a call comes in
Asterisk.

Apply this fix to Jingle too.

Fix the ast_aji_get_client function that was not able to retrieve an
XMPP client from its JID.

(closes issue #12085)
Reported by: junky
Tested by: phsultan


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@119741 65c4cc65-6c06-0410-ace0-fbb531ad65f3