Update to hazelcast-2.5.1.jar.
Configure logging and change hz instance creation.

- Use full qualified class name for Config to avoid RbConfig warnings.
- Use Hazelcast.new_hazelcast_instance to create a new instance instead
  of spawning the default one.
- Add custom log listener that forwards log messages to the dcell
  logger.
- Disable hazelcast system logging and set logging type to 'none' to
  avoid spamming the console.