* Move front-proxy-client certs back to kube mount
We want the same CA for all k8s certs
* Refactor vault to use a third party module
The module adds idempotency and reduces some of the repetitive
logic in the vault role
Requires ansible-modules-hashivault on ansible node and hvac
on the vault hosts themselves
Add upgrade test scenario
Remove bootstrap-os tags from tasks
* fix upgrade issues
* improve unseal logic
* specify ca and fix etcd check
* Fix initialization check
bump machine size
* using separated vault roles for generate certs with different `O` (Organization) subject field;
* configure vault roles for issuing certificates with different `CN` (Common name) subject field;
* set `CN` and `O` to `kubernetes` and `etcd` certificates;
* vault/defaults vars definition was simplified;
* vault dirs variables defined in kubernetes-defaults foles for using
shared tasks in etcd and kubernetes/secrets roles;
* upgrade vault to 0.8.1;
* generate random vault user password for each role by default;
* fix `serial` file name for vault certs;
* move vault auth request to issue_cert tasks;
* enable `RBAC` in vault CI;
