v2.0
Changes:
- oauth_token removed
- access_token and refresh_token added
- use the new steam login api
- use the new json api to get confirmations
- disable retries on get_inventory and get_package to prevent ip ban
- fix is_logged_in method
Minor:
- fix steamworks build on some amd64 machines
- fix default user agent when no http header has been defined
- update tests