main: Write test to exercise runPool helper

[shazow]

Particularly this line:

vipnode/pool.go

Line 227 in c501170

if err := handler.Register("vipnode_", p, "connect", "disconnect", "ping", "update", "peer", "client", "host"); err != nil {

Possibly convert it into an interface like

vipnode/agent.go

Lines 201 to 205 in c501170

	var reverseService agent.Service = runner.Agent
	rpcServer := &jsonrpc2.Server{}
	if err := rpcServer.RegisterMethod("vipnode_whitelist", reverseService, "Whitelist"); err != nil {
	return err
	}