Allow cdr_custom to write to multiple files instead of just one.

Up to now, cdr_custom would only accept a single filename/format from
cdr_custom.conf.  This change allows you to specify multiple filename
& format directives.


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@195165 65c4cc65-6c06-0410-ace0-fbb531ad65f3