Prefer pip to easy_install
Summary:
Prefer pip to easy_install
also fixes incorrect install instructions for closure linters
Test Plan: inspection
Reviewers: avivey, Blessed Reviewers, epriestley, tjstum
Reviewed By: avivey, Blessed Reviewers, epriestley, tjstum
Subscribers: avivey, Korvin
Maniphest Tasks: T10038, T10892
Differential Revision: https://secure.phabricator.com/D15818