setting metadata doesn't support comma-delimeted values

[Jamie Hannaford]

I want to create a server with the following metadata:

groups=k8s-cluster,kube-master,etcd

the value itself is a comma-delimeted string, but because of the way rack handles the --metadata arg, this cannot be done. You get an error like this:

error Invalid flag formatting: Expected key1=value1,key2=value2 format but got kube-master for --metadata.