Support athena workgroups

[nianglao]

AWS release workgroups for Athena to support tags.
https://aws.amazon.com/about-aws/whats-new/2019/02/athena_support_for_tags/
Tagging Workgroups allows you to allocate costs, get detailed billing reports across Workgroups as well as define IAM permissions on Workgroups based on these tags

There is an PR by @jkatagi #26

Can anyone help review and merge this?

[tnosaj]

👍 If the PR is too outdated, i have just forked the current master branch and added workgroup support there #40