We use url.ParseQuery to parse names-to-urls string, but it has side
effect that unescape the string. If the initial-cluster string has ipv6
which contains `%25`, it will unescape it to `%` and make further url
parse failed.
Fix it by modifiying the parse process.
Go1.4 doesn't support literal IPv6 address w/ zone in
URI(https://github.com/golang/go/issues/6530), so we only enable tests
in Go1.5+.
The PR extracts types.Cluster from etcdserver.Cluster. types.Cluster
is used for flag parsing and etcdserver config.
There is no need to expose etcdserver.Cluster public, which contains
lots of etcdserver internal details and methods. This is the first step
for it.
James Shubin