This patch allows for forwarding a message with a "comment" attachment

This patch allows for forwarding a message with a "comment" attachment
if using IMAP storage for voicemail. The comment will be recorded and attached
as a second attachment in addition to the original message. This will be invoked
if you choose to prepend a message the way you would with file or ODBC storage

(closes issue #12028)
Reported by: jaroth
Patches:
      forward_with_comment_v2.patch uploaded by jaroth (license 50)
Tested by: jaroth

git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@114656 65c4cc65-6c06-0410-ace0-fbb531ad65f3