R1:fb2b88a4a81f

Fix Phriction link syntax a little more

Summary: This still wasn't quite right -- a link like `[[ Porcupine Facts ]]` with a space would not lookup correctly, and would render as `porcupine_facts`.

Test Plan: Verified that `[[ Porcupine Facts ]]` now works correctly.

Reviewers: chad

Reviewed By: chad

Differential Revision: https://secure.phabricator.com/D15780