Services do not support custom "pid"-modes (e.g. `--pid=host`), but this
option was ignored silently when deploying a stack.
This patch adds `pid` to the list of unsupported options so that a warning
is printed;
With this patch applied:
$ docker stack deploy -c docker-compose.yml foobar
Ignoring unsupported options: pid
Creating network foobar_default
Creating service foobar_test
Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
70a29b492d