First stab at a conduit method for creating projects.

Summary: This code is mostly lifted from the PhabricatorProjectCreateController.

Test Plan: currently untested

Reviewers: rush898, #blessed_reviewers, epriestley

Reviewed By: #blessed_reviewers, epriestley

Subscribers: epriestley, aklapper, Korvin

Maniphest Tasks: T5691

Differential Revision: https://secure.phabricator.com/D10036