Include "Draft" revisions in Differential legacy status queries

Summary:
See PHI199. Ref T2543. When you run a RevisionQuery with a legacy status constraint (via differential.query), we currently don't match "Draft" revisions.

Use the actual complete map from DifferentialRevisionStatus instead of hard coding the status list so "Draft" is included.

Test Plan:

• Ran differential.query with ids and status for a draft revision.
• Before patch: revision not returned in results.
• After patch: revision returned in results.

(Note that it returns as "Needs Review", for compatibility.)

Reviewers: amckinley

Reviewed By: amckinley

Maniphest Tasks: T2543

Differential Revision: https://secure.phabricator.com/D18765