Set project's ObjectName to its PHID when it doesn't have a hashtag

Summary: Fixes T12659. Previously this would lead to an error when trying to run arc diff on a revision that had a milestone as a reviewer (or any non-octothorpe'd Object Name)

Test Plan: Followed repro steps in T12659 and didn't get the error described. Also clicked around and didn't notice any obvious regressions in projects or differential

Reviewers: epriestley, #blessed_reviewers

Reviewed By: epriestley, #blessed_reviewers

Subscribers: Korvin, yelirekim

Maniphest Tasks: T12659

Differential Revision: https://secure.phabricator.com/D17807