If the argument to the system application is quoted, ensure we remove the...

If the argument to the system application is quoted, ensure we remove the quotes before trying to execute.

(closes issue #16842)
 Reported by: ip-rob
 Patches: 
       20100310__issue16842.diff.txt uploaded by tilghman (license 14)
 Tested by: ip-rob


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@251877 65c4cc65-6c06-0410-ace0-fbb531ad65f3