title: Angular2 selected option in SELECT removed from all other SELECT tags options
body: <p>I have several dropdowns, all have the same initial options. 
  <em>(they may be initialized with one value at the beggining).</em>
  I am looking for solution to a case when choosing one option in one dropdown - it will no longer show as an option in the other dropdowns.
  I saw this solution in AngularJS and didn't succeed making it work in Angular 2 RC 4:
  <a href="https://stackoverflow.com/a/28918935">https://stackoverflow.com/a/28918935</a></p>
  
  <p>In addition I saw that pipes are not recommended for filtering as of Angular.io:</p>
  
  <blockquote>
    <p>The Angular team and many experienced Angular developers strongly
    recommend that you move filtering and sorting logic into the component
    itself.</p>
  </blockquote>