Improve email validation

[VahidN]

Currently email validation is disabled in UserValidator class. new MailAddress part can be replaced with

if(!new EmailAddressAttribute().IsValid(email)) { /*...*/ }

EmailAddressAttribute is part of the new framework.

[Ponant]

Hi, I implemented a custom UserValidator to fix this issue, but I wonder at what date the miltestone 2.0.0 will be honored (approximately, 1 month, 2, 3 ?)

[HaoK]

I believe Q2 2017 is the current forecast, https://github.com/aspnet/Home/wiki/Roadmap

[HaoK]

12aa4a3