Add Asana and Amazon OAuth adapters

Summary:
Ref T1536. Ref T2852. These are pretty straightforward, except:

• Amazon requires HTTPS, and won't let you make an app without an HTTPS callback URI.
• Asana requires "Authorization:" instead of "?access_token" for authorization.

Test Plan: Created Amazon and Asana providers and used them to log in / register.

Reviewers: btrahan, chad

Reviewed By: chad

CC: aran

Maniphest Tasks: T1536, T2852

Differential Revision: https://secure.phabricator.com/D6248