Don't install php5-fpm on precise

Summary:
FPM eats port 9000, which clashes with things (like PresSTORE, ref T2). Since
we aren't using it, just make sure it isn't installed in the first place.

Test Plan: Added acceptance tests.

Reviewers: #macpros_internal, jbowman

Reviewed By: #macpros_internal, jbowman

Subscribers: jbowman

Maniphest Tasks: T2

Differential Revision: http://phabricator.macprofessionals.lan/D9