This adds the Engine version to `docker node ls`, and `.EngineVersion` as a
template option.
With this patch applied:
docker node ls
ID HOSTNAME STATUS AVAILABILITY MANAGER STATUS ENGINE VERSION
wp9231itoqsh4rqceojqo01vp * linuxkit-025000000001 Ready Active Leader 18.01.0-ce
Signed-off-by: Sebastiaan van Stijn <github@gone.nl>