Proxy testing improvements

[feed3r]

in brainclient/brainClient.go

```

detailsEndpoint string
}

func NewClient(brainAddr string, indicatorsEndpoint string, detailsEndpoint string) *Client {

I'm just thinking, not sure about it: maybe we can return *BrainClient instead of *Client? In java i might return the interface instead that the concrete type. But it depends why there is here an interface (so maybe both ways can be ok).