Use AST_CDR_NOANSWER instead of AST_CDR_NULL as the default CDR disposition.

Use AST_CDR_NOANSWER instead of AST_CDR_NULL as the default CDR disposition.

This change also involves the addition of an AST_CDR_FLAG_ORIGINATED flag that is used on originated channels to distinguish: them from dialed channels.

(closes issue #12946)
Reported by: meral
Patches:
      null-cdr2.diff uploaded by mnicholson (license 96)
Tested by: mnicholson, dbrooks

(closes issue #15122)
Reported by: sum
Tested by: sum

git-svn-id: https://origsvn.digium.com/svn/asterisk/branches/1.4@198068 65c4cc65-6c06-0410-ace0-fbb531ad65f3