Allow phlog($a, $b)

Summary: Like `var_dump()`. I guess we would never want to embrace the `print_r()` signature?

Test Plan:
  phlog('It works!', 'a');

Reviewers: epriestley

Reviewed By: epriestley

CC: aran, Korvin

Differential Revision: https://secure.phabricator.com/D5678