Allow semicolons to be escaped, when passing arguments to the System command.

(closes issue #14231)
 Reported by: jcovert
 Patches: 
       20090113__bug14231__2.diff.txt uploaded by Corydon76 (license 14)
       corrected_20090113__bug14231__2.diff.txt uploaded by jcovert (license 551)
 Tested by: jcovert


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@177664 65c4cc65-6c06-0410-ace0-fbb531ad65f3