Create a "New Document" button in phriction

Summary: gives user a dialogue and they can fill out what comes after /w/

Test Plan: made some new wiki docs. played with garbage data and edit scenarios as well as vanilla create -- good ish

Reviewers: epriestley, chad

Reviewed By: epriestley

CC: aran, Korvin

Maniphest Tasks: T1360

Differential Revision: https://secure.phabricator.com/D3946