This fixes a bug with Jitsi and conference calling. Jitsi implements XEP-0298
which places some conference-info information in the session-initiate request
which chan_motif did not expect to occur.
git-svn-id: https://origsvn.digium.com/svn/asterisk/branches/11@372995 65c4cc65-6c06-0410-ace0-fbb531ad65f3