Refactor Galera module

- Implements clustercheck script
- Switch haproxy to clustercheck
- Refactor Galera module
- Fix linting
- Add Rakefile, Gemfile
- Add more settings to wsrep.conf
- Update Modulefile

Change-Id: I14aaf056ec7a086ae07ab699bcb9b8f1403d8490
Implements: bp/galera-improvements
Merge "Refactor Galera module"