Fix UCP upgrade only upgrades one node
Fix UCP upgrade only upgrades one node

Running the UCP upgrade upgrades all managers and workers to the new version, contrary to what is described here. Here is sample output from running this command:

$ docker container run --rm -it   --name ucp   -v /var/run/docker.sock:/var/run/docker.sock   docker/ucp:2.2.12   upgrade --interactive
Unable to find image 'docker/ucp:2.2.12' locally
2.2.12: Pulling from docker/ucp
a073c86ecf9e: Already exists 
fae35fe3a426: Pull complete 
f13c1be613a6: Pull complete 
Digest: sha256:61d4a2e8969a0139187ecf13af8c0020bb7bb5ff5efa2b06e331394a67bd4b68
Status: Downloaded newer image for docker/ucp:2.2.12
INFO[0000] Your engine version 17.06.2-ee-16, build 9ef4f0a (4.4.0-133-generic) is compatible 
INFO[0000] Upgrade the UCP 2.2.5 installation on this cluster to 2.2.12 for UCP ID: sc3nkn5p6rnc33o1e33mnqa1r 
INFO[0000] Once this operation completes, all nodes in this cluster will be upgraded. 
Do you want proceed with the upgrade? (y/n): y
londoncalling/docker.github.io,thaJeztah/docker.github.io,docker/docker.github.io,anweiss/docker.github.io,londoncalling/docker.github.io,anweiss/docker.github.io,anweiss/docker.github.io,thaJeztah/docker.github.io,anweiss/docker.github.io,thaJeztah/docker.github.io,docker/docker.github.io,anweiss/docker.github.io,docker/docker.github.io,docker/docker.github.io,londoncalling/docker.github.io,londoncalling/docker.github.io,docker/docker.github.io,thaJeztah/docker.github.io,londoncalling/docker.github.io,thaJeztah/docker.github.io