ionic2 angularfire example better than google example..............

https://github.com/rodrigoreal/ionic2-angularfire-login




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https://github.com/angular/angularfire2/issues/560
https://blog.khophi.co/angularfire2-authentication/

https://github.com/angular/angularfire2/issues/568

https://github.com/angular/angularfire2/issues/566