Set php PATH for repository's hook

Summary:
Set PATH for repository's hook, so the environment.append-paths can used
repository's hook may can't find php path if user's profile like bash_profile is not loaded.

Test Plan: check the hook generated is contain the right path

Reviewers: epriestley, #blessed_reviewers

CC: Korvin, epriestley, aran

Differential Revision: https://secure.phabricator.com/D7743