`make bin` broken w/ latest zookeeper client

[jbeda]

I'm trying to build from sources and it looks like make bin doesn't use the vendored dependencies (but make test does). Things are currently broken:

$ go get -v ./...
github.com/hashicorp/vault/physical
# github.com/hashicorp/vault/physical
physical/zookeeper.go:299: undefined: zk.StateSyncConnected

[jbeda]

Looks like zk.StateSyncConnected is unused and was removed in samuel/go-zookeeper#65. I'll submit a PR.