Housekeeping:
* Use newer http-conduit (Request m becomes Request)
* Increase upper bound on aeson
* Fix whitespace, remove unfinished function
* Add type signatures and some comments
* Remove unused imports
Fixes:
* ByteString needs an orphan JSON instance so AccessToken can have one.
I'm not sure if there's a way around this.
* redirect takes a Text, not a ByteString
* dispatch for "callback" should handle setting the credentials
Additions
* oauth2Learn for authenticating against learn.thoughtbot.com