Clean up misc Ponder details

Summary: Ref T3578, Changes "Ask Away" to just "Submit", Changes Description to Details, check for is_new when offering closed state on question edit.

Test Plan: New Question, Edit Question

Reviewers: epriestley

Reviewed By: epriestley

Subscribers: Korvin

Maniphest Tasks: T3578

Differential Revision: https://secure.phabricator.com/D13891