R1:8821ab57c00f

Allow speical keys to be bound to keystrokes

Summary: Fixes T2711. Allows special keys (arrows, tab, return) to be bound as shortcuts. Binds left and right as shortcuts in Pholio.

Test Plan: Pressed left. Pressed right.

Reviewers: chad

Reviewed By: chad

CC: aran

Maniphest Tasks: T2711

Differential Revision: https://secure.phabricator.com/D5303