Registering with more information

[Roshyo]

We should be able to register to MailChimp with at least lastName + FirstName.
If implemented, here is how it should behave :

Case1: Already logged in

• Display just the register button (since we already have email + last name)

Case 2: Not logged in

• Display lastName + email
• If email matches a customer, fetch it, and use this last name w/e we filled in input
• If email does not match, create a customer with email + lastName and add it as a contact
• Register email to newsletter if not already there