Client does not support bearer token authentication #147

Couple issues here.

1. README example has NewClient(ApiKey, ""). Code wants NewClient(AppID, ApiKey). The former is the only think that "worked" for me. This still doesn't return anything despite "successful" calls.
2. The IntercomHTTPClient mechanics are misleading and do not match the API documentation's guidance to use Bearer token authorization. More below.

func (c IntercomHTTPClient) Get(url string, queryParams interface{}) ([]byte, error) {
	// Setup request
	req, _ := http.NewRequest("GET", *c.BaseURI+url, nil)
	req.SetBasicAuth(c.AppID, c.APIKey)
	req.Header.Add("Accept", "application/json")
	req.Header.Add("User-Agent", c.UserAgentHeader())
	addQueryParams(req, queryParams)
	if *c.Debug {
		fmt.Printf("%s %s\n", req.Method, req.URL)
	}

	// Do request ...

func (r *Request) SetBasicAuth(username, password string) {
	r.Header.Set("Authorization", "Basic "+basicAuth(username, password))
}

As it stands, it seems I need to implement my own intercom interfaces.HTTPClient interface to refactor Get, Post, Patch, Delete functions. Or get a change into this repo or some fork to properly use Bearer authorization. This repo doesn't seem maintainer but this does seem important for basic functionality. (Removing my star :( )