attended transfer use transferer context first and set who is transfering at...

attended transfer use transferer context first and set who is transfering at the beginning (issue #6752 reported by moy -- minor mods done by myself)


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@30548 65c4cc65-6c06-0410-ace0-fbb531ad65f3