DTMF transfer plays the wrong sounds for wrong number or other call failure.

DTMF transfer plays the wrong sounds for wrong number or other call failure.

* Set the default for features.conf.sample xferfailsound option to "beeperr"
as documented instead of "pbx-invalid" and corrected the use of it in DTMF
blind transfer (#1).

* Improved DTMF blind transfer handling of wrong numbers.

Most of the concerns in this issue were taken care of by the patch for
issue 17999: Issues with DTMF triggered attended transfers.

(closes issue #18379)
Reported by: gincantalupo
Tested by: rmudgett

git-svn-id: https://origsvn.digium.com/svn/asterisk/branches/1.4@302671 65c4cc65-6c06-0410-ace0-fbb531ad65f3