refactor vault role (#2733)

* 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

tests/files/gce_coreos-vault-upgrade.yml

@@ -0,0 +1,13 @@
+# Instance settings
+cloud_machine_type: "n1-standard-4"
+cloud_image_family: coreos-stable
+cloud_region: us-central1-b
+mode: aio
+
+# Instance settings
+bootstrap_os: coreos
+cert_management: vault
+kube_network_plugin: flannel
+deploy_netchecker: true
+kubedns_min_replicas: 1
+cloud_provider: gce