Implement a real autoupdater (MacOS)

[xmppler]

Please implement the excellent autoupdater framework Sparkle. ​http://sparkle.andymatuschak.org/

Otherwise you could remove the current update checker at all - it's useless. I always read on a newssite that there is a new version of virtualbox and the builtin update checker still tells me "your version is current".

[Frank Mehnert]

The current policy is as intended. The version notifier will be increased once we are sure that the new release doesn't contain any critical regressions.