Added the S() and L() options to the MeetMe application. These are pretty

Added the S() and L() options to the MeetMe application.  These are pretty
much identical to the S() and L() options to Dial().  They let you set
timeouts for the conference, as well as have warning sounds played to
let the caller know how much time is left, and when it is running out.

(closes issue #8030)
Reported by: areski
Patches:
      meetme_timeout_timelimit_v2.patch uploaded by areski (license 29)

git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@89069 65c4cc65-6c06-0410-ace0-fbb531ad65f3