Make "Create Document" in Phriction use workflow

Summary:
My claims that this worked on D4183 were incorrect:

• Make it work.
• Then use it.
• Also make cancel URI not cancel to the same page.

Test Plan: Clicked "Create Document", got a workflow on-page dialog instead of a page transition.

Reviewers: codeblock

Reviewed By: codeblock

CC: aran

Differential Revision: https://secure.phabricator.com/D4403