Fix Diviner issue when publishing new atoms

Summary: We need to make sure the symbol is always saved before the atom. I mucked this up recently and didn't catch it locally since I'd already generated the atoms.

Test Plan: Ran bin/diviner generate after truncating all diviner tables.

Reviewers: chad

Reviewed By: chad

CC: aran

Differential Revision: https://secure.phabricator.com/D6146