Make the new synthetic burnup chart data respect the "Project" filter

Summary: See PHI273. Third time's the charm? This page has a "Project" filter which lets you view data for only one project, but the synthetic data currently ignores it.

Test Plan: Filtered burnup chart by various projects, saw sensible-looking data.

Reviewers: amckinley

Reviewed By: amckinley

Differential Revision: https://secure.phabricator.com/D18860