add a global option to disable priority jumping in applications (when they get updated), settable in extensions.conf
change app_dial to use 'j' to _ENABLE_ priority jumping if it has been globally disabled


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@6224 65c4cc65-6c06-0410-ace0-fbb531ad65f3