etcd version variable

Description

auto-updater have problem with version on etcd image. It's stored in two variables:

etcd_version: "3.1.1"

_etcd_image: "quay.io/coreos/etcd:v{{ etcd_version }}"

It's good that it is stored in two variables, but auto-updater updates version based on tag names. Tag names in etcd starts with v. So auto-updater changes variable like this:

etcd_version: "v3.2.2"

Proposal

Change those two variables by moving v from _etcd_image to etcd_version. Like this:

etcd_version: "v3.1.1"

_etcd_image: "quay.io/coreos/etcd:{{ etcd_version }}"