Phriction setting.

Summary: One setting.

Test Plan:

• Looked at the setting in the web interface.
• Waved to it
• Introduced myself
• Had a nice conversation
• Made a new friend
• Turns out phriction.enabled is a nice guy.

Reviewers: epriestley, chad

Reviewed By: chad

CC: aran, Korvin

Maniphest Tasks: T2255

Differential Revision: https://secure.phabricator.com/D4436