Add verifyEmailAddress option to accounts.signup()

[rglover]

Idea:

  accounts.signup({
    emailAddress: '[email protected]',
    password: '123',
    verifyEmailAddress: true,
  });

If this is true, automatically try to send off an email to address using config.email settings, or, log a warning to the console to say settings are missing. User gets an email with a confirmation email at something like /_api/accounts/verify?token=1234. When they click the link, go to that route and then update the DB with verified: true on their user record.