Provide new tool "bin/user approve" to approve an account.
This method uses the existing transaction. As such, most of the testing focused on the integration between the workflow and transaction. The only change made to the transaction was to allow an omnipotent user to make the change in addition to an admin.
Other than that, I removed the "approved" flag from the user, then ran the command-line utilty until the user was successfully approved.
Reviewers: Blessed Reviewers, epriestley
Reviewed By: Blessed Reviewers, epriestley
Subscribers: Korvin, epriestley
Maniphest Tasks: T13578
Differential Revision: https://secure.phabricator.com/D21587