[Feature request] Allow changing the user's email address

[mrhappyasthma]

Following up on #28, we should update the loader to support changing the email address.

NOTE: This will require changes to the Darkstar connect server.

NOTE2: The accounts SQL table contains two email fields (email, email2). One of the fields should store the original sign-up email to use for account recovery purposes. The other can be updated to hold the current email.