R1:a3b955f948c8

Add Spaces to Ponder

Summary: Ref T8493, Ref T3578. Adds spaces support to ponder.

Test Plan: Ask a question in a new space, see new question.

Reviewers: epriestley

Reviewed By: epriestley

Subscribers: Korvin

Maniphest Tasks: T3578, T8493

Differential Revision: https://secure.phabricator.com/D13792