stolon v0.9

• Upgrade stolon to v0.9
• Making clusterName parameter optional
• generate repl password
• refactor labels and selectors to follow helm best practices
• add antiaffinity definitions
• update volumeClaimTemplates to use storageClassName
• update template helpers to follow helm best practices
• add configuration stubs for nodeSelector and tolerations
• fix pgParameters when ssl or slow queries are not specified

thanks to @Elexy and @rtluckie for their work