internal/clusterinfo: make public

[nvcnvn]

I writing a "nsq_to_db" tool with Golang which is very similar to "nsq_to_file" but sadly the "github.com/nsqio/nsq/internal/clusterinfo" pacakge is internal package. I know that the "internal/clusterinfo" pacakge is the client tool for NSQ HTTP interface, it seem a good usage for Golang client sub pacakge?

[mreiferson]

@nvcnvn might make sense to make that public, we've taken this position to avoid issues of compatibility guarantees, but this package could be generally useful.

What do you think @jehiah ?

[blide]

Any updates?