Add 'kick all' capability to ConfBridge CLI command

This patch adds the ability to kick all users out of a conference from the
ConfBridge kick CLI command. It is invoked by passing 'all' as the channel
parameter to the CLI command, i.e., "confbridge kick <conf> all".

Note that this patch was modified slightly to conform to trunk.

(closes issue ASTERISK-21827)
Reported by: dorianlogan
patches:
  kickall-patch_v2.diff uploaded by dorianlogan (License 6504)


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@394531 65c4cc65-6c06-0410-ace0-fbb531ad65f3