Add support for Docker Swarm

[fmartinou]

Would you be interested in the support of Docker Swarm?

• WUD doesn't read from deploy labels for Docker Swarm #436
• Welcome to wud Discussions! #461 (comment)
• Feature Request - Add stack to the UI #489

[JonS1156]

I'm interested in this. Setting one up now and the other solutions want to use an aditional container for notifications which I'm not a fan of.