MacGui: Move app support directory check to -init in controller.mm

MacGui: Move app support directory check to -init in controller.mm
- Makes ~/Library/Application Support/HandBrake available to HBOutputPanelController immediately
- Elimates duplicate code to check for app support directory for both the presets as well as the activity log (as well as any other future features that will require this directory)
- Also fixed issue where clicking "Discard" in the update alert closes the main window and won't let it come back (this will be totally unnecessary once the Sparkle update system is implemented).

git-svn-id: svn://localhost/HandBrake/trunk@1061 b64f7644-9d1e-0410-96f1-a4d463321fa5