add support for refresh token

[vgrafe]

First of all, thanks for this great library, the struggle was so real before I came across your nextjs example!

As requested in sandrinodimattia/nextjs-auth0-example#2 :

A good feature for the next release would be to store refresh token, in order to allow getting new access tokens when needed.

[sandrinodimattia]

Fixed in v0.2.0. You'll want to request the offline_access scope in addition to any other scopes and then set storeRefreshToken to true.

There's some additional things we're tracking here: #7

[sandrinodimattia]

Let me know if we can close this issue.

[vgrafe]

That was fast!! I'll have a look after work.

[b2times4]

Brilliant + fast = brilliant.
I'll (kindly) "need" sandrinodimattia/nextjs-auth0-example to be updated for implementation.
I managed to get the example implemented as is, but brain not large enough to update it with refresh_token

[vgrafe]

Just tried 0.2.0, perfect! I can see the token in the JTW session. You can close.

@b2times4: you might want to file an issue in the repo you linked. I'll mention you if I find myself figuring out a working example of token refresh.

[sandrinodimattia]

We now have a full example available that shows how to get a valid access token (and if expired, automatically get a new one using a refresh token):

https://github.com/auth0/nextjs-auth0/blob/master/examples/api-call-example/pages/api/shows.js#L9-L11

I'm going to go ahead and close this issue now.