Add a verify email workflow to accounts

[rglover]

This was just an oversight on the initial implementation, but should come standard. Needs:

• [x] emailVerified field added to all new users by default
• [x] An accounts.send_email_verification() method for sending a verify email (should respect existing /emails/verifyEmail.js template or fallback to plain text and just pass token via props to the email template).
• [x] An accounts.verify_email() method for validating a verification token (should exist in joystick.js/ui and joystick.js/node).

[rglover]

Also include #280 in this work