Support for multiple email addresses for one account

[Yihang Wang]

Thanks for creating such a great software.

I found that RaiDrive does not support to add an alternative email, It would be useful for someone who has multiple affiliates (eg: a student who has his/her personal Gmail account and a school email, when he/she graduate from the institution, he/she MUST register another new account if he/she still wants to use RaiDrive).