Resolve using service tags on Consul

[vectorhacker]

It would be nice if resolving using tags in consul would be implemented. Perhaps by setting the name of the service in the same format as a consul srv record. Something like:

b := wonaming.NewResolver("v1.users")

This is nice for when you want to have multiple versions of a service and you want the clients to connect to those. It's a far nicer format that renaming the services in consul. I could make a pull request later on if you'd like this feature.

[elvizlai]

@vectorhacker
In etcd we have a public variable named "Prefix" to indicate the 'version of service' (a group of service).

https://github.com/wothing/wonaming/blob/master/etcd/register.go#L21

Feel free if you'd like to send a PR in consul.

[fho]

@vectorhacker https://github.com/simplesurance/grpcconsulresolver also supports tags