Minor improvements to email management interface

Summary:

• If you have an unverified primary email, we show a disabled "Primary" button right now in the "Status" column. Instead we should show an enabled "Verify" button, to allow you to re-send the verification email.
• Sort addresses in a predictable way.

Test Plan:

• Added, verified and removed a secondary email address.
• Resent verification email for primary address.
• Changed primary address.

Reviewers: btrahan, csilvers

Reviewed By: btrahan

CC: aran

Maniphest Tasks: T1184

Differential Revision: https://secure.phabricator.com/D2548