Ability to change customer roles to Admin

At the moment, the users who sign up themselves, are not allowed to be edited by Admins. While the Admins, should not be able to edit their email/name - but they should be allowed to make some customers, Admins of the system.

This case is valid where a colleague might have signed up by themselves as customers, but they now need an Admin account.

@mark-morse A small change, but we just added this ☝️

Love this. Thanks Pranav!

@shashank-sharma-1 Fuck yeah