Optional light colored background, for those who use black on white terminals.

(closes issue #13306)
 Reported by: Corydon76
 Patches: 
       20080814__bug13306__3.diff.txt uploaded by Corydon76 (license 14)
 Tested by: Corydon76, pkempgen


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@139981 65c4cc65-6c06-0410-ace0-fbb531ad65f3