Move "Send Welcome Email" to profiles and nuke old weird edit UI

Summary: Ref T4065. Moves the last of the weird alternate edit UI to profiles. The old "Edit" controller is now for creation only, and the funky pencil icon is gone.

Test Plan: Created accounts; sent welcome email.

Reviewers: btrahan

Reviewed By: btrahan

Subscribers: epriestley

Maniphest Tasks: T4065

Differential Revision: https://secure.phabricator.com/D8670