Refactor access token rewrite and id_token

[BobbyMcWho]

While the approach in #24 and #17, worked I was a bit perplexed on why in the first place we were creating a new token from the old one, overwriting Strategies::OAuth2's @access_token attr_reader, and creating a new token that is essentially identical to the old one.

I've removed that method alias/overwrite, rely on the access_token that the base OAuth2 strategy gives us, and properly access the id_token on the access_token.

I've also fleshed out the specs a bit more, to validate that things are working as expected w/ the deleted access_token method.

I've released 2f11b42 on RubyGems as v2.0.0.rc1

[BobbyMcWho]

Closing to run CI

[ryanswood]

@BobbyMcWho Glad you went that extra step to simplify the handling of the access token. The change here looks good. Thank you for working with us to make this happen.

[BobbyMcWho]

@ryanswood if you wouldn't mind trying out the release candidate, I can merge and release an official sometime next week. I don't have access to a production app with Okta oauth these days, else I'd validate

[ryanswood]

@BobbyMcWho I was out Friday and see this has now been merged with an official 2.0 release. Thank you for working with us to make this change. I was able to test it and all is well.