Passport strategy for Instant Login with Clever

Install the package via npm: npm install passport-clever

Initialize the strategy as follows:

```js
const CleverStrategy = require('passport-clever');
passport.use(new CleverStrategy({
    clientID: "",
    clientSecret: "",
    callbackURL: "",
    passReqToCallback: true
}, function(req, accessToken, refreshToken, profile, cb) {
cb(null, accessToken);
}));
```

Add the login route: app.get("/login", passport.authenticate('clever'));

This repository is NOT developed, endorsed by, or even related at all to Clever. This library was implemented solely by the community's hardwork, and based on information that is public on Clever Developer's website. The library merely acts as a helper tool for anyone trying to implement Clever's Instant Login.