- Removed Growl framework. No longer needed since our deployment target is now 10.9.
- Removed showStickyMessage from SystemNotification as the type of the message is not switchable (there's only one style for all messages) and the user can set that to any allowed style, so we may not be allowed to show a button or stay on the screen until the user confirms (e.g. for serious problems). Use a normal alert panel in that case.
- Removed unused context parameter in SystemNotification.