Modernize PhortuneAccount with EditEngine/Modular Transactions

Summary: This updates the backend of PhortuneAccount to use EditEngine and Modular Transactions and updates language to "account manager" for clarity of role.

Test Plan:

• Wiped phortune_account table
• Visit Phortune, see new account automatically created.
• Edit name and managers
• Try to set no name or remove myself as a manager, get error messages
• Visit /phortune/ and create another new account

Reviewers: epriestley

Reviewed By: epriestley

Subscribers: Korvin

Differential Revision: https://secure.phabricator.com/D17585