Refresh flow is broken

[guitmz]

Hey!

So I saw this: #37 and I was like "nice, it should be working". Sadly, it isn't (and I really need to use the refresh token). The PR included in the issue I've mentioned does not even make sense, it basically just declare a few variables and interfaces and called it a day.

There are a lot of problems with your current request method that won't allow an easy implementation of refreshToken (wrong content-type, wrong way of sending the body to the request, etc), I've just forked your project and got some progress but unfortunately I'm stuck in unmarshaling the response body. Perhaps it would be easier to write an entire different request function only for the refresh flow meanwhile, I don't know.

I'll not provide a PR for this (as of now) because I'm still figuring out your code, the progress I made so far, while workable, is ugly hahaha So consider this issue a feature request for now. I'll provide updates if I get some progress but I believe you can easily fix the refresh flow on your end in half hour.

Nice code by the way :)

EDIT: here's a PR with a (ugly but working) fix: #41