This patch adds the ability to send a CUSD command to a bluetooth device.

(closes issue #15278)
Reported by: Artem
Patches:
      cusd5.patch uploaded by Artem (license 800)
Tested by: mnicholson, Artem

Review: https://reviewboard.asterisk.org/r/274/


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@209484 65c4cc65-6c06-0410-ace0-fbb531ad65f3