title: Angular (4): disable the whole form (group) instead of each input separately?
body: <p>Is it possible to disable the whole form (group) in angular instead of doing it for every input separately? </p>
  
  <p>Something like <code>&lt;input [disabled]="formNotValid"/&gt;</code> but for a <code>&lt;form&gt;</code> or a <code>&lt;div ngModelGroup..&gt;</code>? </p>