Remove code to set timezone?

Just a suggestion: this role (ansible-elasticsearch) sets the server timezone.

There are already a number of roles in Ansible Galaxy that perform this task (e.g. https://galaxy.ansible.com/Stouts/timezone/) so maybe setting the timezone could be left to another role?
It would help simplify the codebase.

PS Great work on writing this role BTW - it saved me a lot of effort!
