Further reduce the encoded blank values back to blank in the realtime API.

(closes issue #16533)
 Reported by: sergee
 Patches: 
       200100104__issue16533.diff.txt uploaded by tilghman (license 14)
 Tested by: sergee


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@237410 65c4cc65-6c06-0410-ace0-fbb531ad65f3