Remove util.inherits about node-oauth2-server

[dsschiramm]

I'll start with this issue ok?
Seems like a good start for me (first time in a project doing something in an opensource project)

[jankapunkt]

Since #58 is merged I could start working on this on a new branch

[HappyZombies]

Wouldn't this require to change these functions to be class AuthorizationCodeGrantType extends AbstractGrantType?

[jwerre]

Yes.

[Uzlopak]

Try out https://lebab.unibtc.me/editor

[dsschiramm]

Should I change the way the import is written as well?

Example:
const AbstractGrantType = require('./abstract-grant-type');
To
import AbstractGrantType from './abstract-grant-type';

Or should I leave this change for another issue/pull request?

[Uzlopak]

Dont change, as it would just open the whole can of worms of esModule imports potentially breaking while running on node because of some reasons.