Please complete authentication features

ros

#22

Pushing this, just in case it was forgotten.


#23

@ischuetz We have the documentation for the server side here:
https://docs.realm.io/platform/v/3.x/self-hosted/customize/authentication/username-password/password-reset-and-email-confirmation

The HTTP API has been wrapped in a convenience SDK API for all the bindings, you can find it as the changePassword method off the SyncUser object:
https://realm.io/docs/java/5.1.0/api/