R1:8d20e42c1c0a

Fix a MySQL strict issue with auxiliary task storage

Summary: This table has date columns but we don't populate them correctly. In strict mode with custom fields, this throws when creating a task.

Test Plan: Created a task in strict mode with custom fields.

Reviewers: chad, vrana

Reviewed By: vrana

CC: aran

Differential Revision: https://secure.phabricator.com/D5137