Add OAuth Token API

Review Request #9078 — Created July 17, 2017 and submitted — Latest diff uploaded

Information

Review Board
release-3.0.x

Reviewers

The OAuth2 token APi allows users to view and manage their current
OAuth2 tokens. This API is intentionally limited: the only update
operation is to change the scope and the only other options is to delete
the token.

Ran unit tests.