coinbase.go
func ApiKeyClient(key string, secret string) Client {
	c := Client{
		rpc: rpc{
			auth: apiKeyAuth(key, secret),
			mock: false,
		},
	}
	return c
}
func ApiKeyClient(key string, secret string) Client {
	c := Client{
		rpc: rpc{
			auth: apiKeyAuth(key, secret),
			mock: false,
		},
	}
	return c
}
// ApiKeyClient instantiates the client with ApiKey Authentication