integration-on-swarm had unnecessary complexity and was too hard to
maintain. Also, it didn't support the new non-CLI integration test suite.
I'm now doing some experiments out of the repo using Kubernetes:
https://github.com/AkihiroSuda/kube-moby-integration
Signed-off-by: Akihiro Suda <akihiro.suda.cz@hco.ntt.co.jp>