This is a part of the etcd_ like role consolidationi into an action-based role.
As part of the consilidation some roles have been removed and some replaced by
include_role module. Resulting in reorder and shift of role dependencies
from a role into a play.

- introduce block and simplify when conditions
- introduce config.yml so the self-standing etcd role can be run (e.g. to test etcd cluster deployment)
- remove empty task files
- skip dependency on openshift_etcd_ca
- replace cert paths with their appropriate variables