title: Angular2 reactive form containing a list
body: <p>I am attempting to create a form for a user that will allow one to may phone numbers to be associated with the user. Is this possible with the current implementation of reactive forms? For example, I would want the below form to accept potentially many phone numbers. My front end implementation would show the phone number field, and would have a button that would allow for an additional phone number field to be added.</p>
  
  <pre><code>userForm = new FormGroup({
    firstName: new FormControl('', Validators.required),
    lastName: new FormControl('', Validators.required),
    phoneNumber: new FormControl('', Validators.required)
  });
  </code></pre>
  
  <p>My hack solution would be </p>
  
  <pre><code>userForm = new FormGroup({
    firstName: new FormControl('', Validators.required),
    lastName: new FormControl('', Validators.required),
    phoneNumber: new FormControl('', Validators.required),
    phoneNumber1: new FormControl(),
    phoneNumber2: new FormControl(),
    phoneNumber3: new FormControl(),
    phoneNumber4: new FormControl()
  });
  </code></pre>
  
  <p>I could suppress the additional phone fields until the add an additional phone number button is clicked.</p>