Confbridge CLI new record file name check.

This fix checks to make sure that if a confbridge record start command is issued
from the CLI it will always use the file name given on the CLI even if it
changes between start/stop records for a conference.  Previously it had been
reusing the same file between start/stops even if a new filename was given.

(issue AST-1088)
Reported by: John Bigelow


git-svn-id: https://origsvn.digium.com/svn/asterisk/branches/11@382385 65c4cc65-6c06-0410-ace0-fbb531ad65f3