Modernize email verification page

Summary: Fixes T3517. Moves the email verification page out of People and into Auth. Makes it look less awful.

Test Plan: {F49636} {F49637}

Reviewers: chad, btrahan

Reviewed By: btrahan

CC: aran

Maniphest Tasks: T3517

Differential Revision: https://secure.phabricator.com/D6425