Let the api to choose the default network driver.
Let the api to choose the default network driver.

That way swarm can understand the user's intention.

Signed-off-by: David Calavera <b9b0c8e7f90ecf337f6797c4d2e0f1dd0dbc0324@gmail.com>
(cherry picked from commit 34668ad68bb42d7488649e41b32818f3f1a7cff2)

circleci/docker,solanolabs/docker,solanolabs/docker,solanolabs/docker,makinacorpus/docker,circleci/docker,makinacorpus/docker,makinacorpus/docker,circleci/docker