Merged 5 Sparkle forks and 7 pull requests (in a maintained fork)

* Merged bugfixes, security fixes and some features from 5 Sparkle forks and 7 pull requests.
* Merged quiet-automatic-update branch.
* Up to date with 10.9 SDK and Xcode 5.1.
* Name of finish_installation.app can be configured to match your app's name.

* Removed warning about the lack of maintenance, because I'm maintaining it :)