MacGui: use FSEvent api to create a FSEventStream to keep track of when a file inside the Queue folder is update. Move Queue.plist inside a folder because FSEvent can only track changes at folder level, so we have a folder with just a file inside.
Whenever something happens inside the Queue folder, HandBrake reload Queue.plist.

git-svn-id: svn://svn.handbrake.fr/HandBrake/trunk@5720 b64f7644-9d1e-0410-96f1-a4d463321fa5