Ensure line terminators in email are consistent.

Ensure line terminators in email are consistent.

Fixes an issue with certain Mail Transport Agents, where attachments are not
interpreted correctly.

(closes issue #16557)
 Reported by: jcovert
 Patches:
       20100308__issue16557__1.4.diff.txt uploaded by tilghman (license 14)
       20100308__issue16557__1.6.0.diff.txt uploaded by tilghman (license 14)
       20100308__issue16557__trunk.diff.txt uploaded by tilghman (license 14)
 Tested by: ebroad, zktech

Reviewboard: https://reviewboard.asterisk.org/r/544/

git-svn-id: https://origsvn.digium.com/svn/asterisk/branches/1.4@255591 65c4cc65-6c06-0410-ace0-fbb531ad65f3