Use oauth2 client with test adapter for #extra spec
Pass id_token inside #extra
Use earlier version of Rubygems

* Lifted from https://github.com/freerange/mocha/commit/66bab2a8f4e7cd8734bf88e6f32157c0d5153125
Merge pull request #85 from minifast/add_id_token_to_extra

Add id_token to #extra