Add Stage field to a review request

Review Request #8495 — Created Oct. 26, 2016 and discarded — Latest diff uploaded

Information

Review Board
master

Reviewers

This feature will add a stage field to a review request that will provide some
context as to where a review request is in its development/review lifecycle.
This field provides visual information that will aid decision making on a
review request like whether to perform an automatic code review or wait for
the author to make changes.

This feature adds built-in stages which are
- ApprovedStage
- CompletedStage
- DiscardedStage
- PendingChangesStage
- PendingReviewsStage
- UnpublishedStage
- WIPStage

All tests pass