Stop calling apc_store() with an array

Summary: Older versions of APC (AND HPHP) don't like apc_store() being called with an array, so it's easier to just foreach it each time.

Test Plan: make sure nothing breaks

Reviewers: epriestley

Reviewed By: epriestley

CC: aran, Korvin

Differential Revision: https://secure.phabricator.com/D5581