Phortune - fix fatal from initial load

Summary: the attachX upgrade means we need to blank this out formally when creating a new object. Fixes https://github.com/facebook/phabricator/issues/383

Test Plan: loaded phortune for the first time - no fatal and it worked!

Reviewers: epriestley

Reviewed By: epriestley

CC: Korvin, aran

Differential Revision: https://secure.phabricator.com/D6939