Email migrations

- [x] DB Schema migration (add `send_notifications` boolean)
- [x] DB Data migrations (move primary emails to `emails` table)
- [x] Use only `emails` table
- [x] Before_save hook: lowercase
- [x] Migration: lowercase emails
- [x] Backend: can_delete_email?
- [x] can_delete_email should take into account the email confirmation status
- [x] [Mikko] Bug: Error message "you must have at least one notification email" UI broken
- [x] [Antti] Bug: No confirmation is sent when user adds a new email
- [x] [Mikko] Add tests to resend
- [x] Missing translations
- [x] Make sure responsive layout works (desktop & Mobile)
- [x] Bug: When confirming a welcome email was sent (and as I was admin it brought the "Olet juuri perustanut yhteisön" mail. (Not sure if this happens to non-admins too)