[1.3.0] Allow creation, updating, and deletion of cluster admins

* Adds new influxdb_admin LWRP
Merge pull request #3 from SimpleFinance/cluster-admin

[1.3.0] Allow creation, updating, and deletion of cluster admins
Use 'client' over 'cli' in providers
Merge pull request #6 from SimpleFinance/clear-var-names

Use 'client' over 'cli' in providers
Merge branch 'master' into user-updates
[1.4.0] Add databases to :delete for user, use 'client' over 'cli'