Add Telenet login provider

[mediaminister]

This is an attempt to support Telenet-logins in the Streamz Kodi add-on. I don't have a Telenet subscription myself, so I'm not sure if this works.

Fixes #1

[michaelarnauts]

It seems I still have a working TN login (I can login on the telenet.be portal) from a while ago when I was a Telenet customer. After logging in in the browser, I get a message that I don't have access to streamz, but I could probably validate this authentication flow with this.

I'll try to do this in the course of next week.

[michaelarnauts]

There are two different kind of tokens. An login token that you get from https://login.streamz.be/authorize, and the actual token we get from the cookie when going to https://www.streamz.be/streamz/aanmelden. I think only the first flow is different for Telenet, and once we get a login token, we can use the same code.

[mediaminister]

Indeed, thanks for fixing. It would be good if more people can test this as I don't have a Telenet subscription myself.