1). Register a shutdown handler to run system.shutdown events. Refs #2103
2). Automatically save logs on system shutdown. Fixes #2091
3). Made session library use the system.shutdown event instead of registering it's own shutdown handler. Fatal exceptions now use the system.shutdown event as well.
4). Clean up static inconsistencies. Refs #2088
- Bug Report #2088: Static references are inconsistent
- Bug Report #2091: Optimize Kohana_Log by running save on system.shutdown event
- Feature Request #2103: Use a shutdown handler to run system.shutdown