add version to environment file

Trigger reboot handler when version upgrade during update script

roles/etcd/templates/etcd.env.j2

+# Environment file for etcd {{ etcd_version }}
 ETCD_DATA_DIR={{ etcd_data_dir }}
 ETCD_ADVERTISE_CLIENT_URLS={{ etcd_client_url }}
 ETCD_INITIAL_ADVERTISE_PEER_URLS={{ etcd_peer_url }}