Parse arguments passed to the CDR_PROP function correctly

Parse arguments passed to the CDR_PROP function correctly

I can only blame this on a bad merge, because this in no way worked properly
the way it was written. Mea culpa. The function should now parse its arguments
correctly and function properly. (Note that the API used by the CDR_PROP
function has working unit tests... this was merely bad coding of the actual
registered function)

(closes issue ASTERISK-22613)
Reported by: Private Name

git-svn-id: https://origsvn.digium.com/svn/asterisk/branches/12@400196 65c4cc65-6c06-0410-ace0-fbb531ad65f3