Refactor: Rename `getToken` to `authorize`

[andrewxhill]

There is a bit of confusion about the point of getToken. It appears on its face to be something more like an authenticate api. However, a user's token doesn't need to change, so you only technically have to get a user their token one single time in their lifetime in the app. So, what's a good way to clarify this api?

Maybe getToken shouldn't live on the the Database/Client classes? It might be nice to have a User class for something like getToken and then more explicitly on Client just a setToken... That's just one idea though.

[andrewxhill]

I've settled on these terms

authenticate is what the developer does with the hub api. they authenticate with their api key/secret

authorize is what the developer does with a user identity and the api. they authorize a user identity to use their hub api endpoint for a period of time.

so i think getToken should just become client.authorize(identity)

[carsonfarmer]

This is being done as part of The Great Refactor (#414) work.