Feature Request: Cloud Function should support user.sendEmailVerification() like client sdk

[Refiling for user @sun3 from https://github.com/firebase/functions-samples/issues/181]

Feature Request:

The ```user.sendEmailVerification()``` needs to be supported by Firebase Cloud Functions. This is available in client side but not server side. When using Cloud Functions to create new users we also need to automatically send Email Verification before new user can use our apps. This is currently as stopping block for our apps.

At this point the ```user.sendEmailVerification()``` gives error that function is not found.

```
admin.auth().createUser({
email: emailAddress,
emailVerified: false,
password: password,
displayName: '', //name,
disabled: false
})
.then(function (user) {
// A error representation of the newly created user is returned
console.log("Created Firebase User successfully with id: ", user.uid);
console.log("user.emailVerified:", user.emailVerified);

// Send Email Verification
user.sendEmailVerification()
.then(function (emailSent) {
console.log('emailSent ', emailSent);
})
.catch(function (error) {
console.log('emailSent error ', error);
});

// ... Additional code below
```

Thank you and I am open to any suggestions.