title: Filter object properties by key in ES6
body: <p>Let's say I have an object:</p>
  
  <pre><code>{
    item1: { key: 'sdfd', value:'sdfd' },
    item2: { key: 'sdfd', value:'sdfd' },
    item3: { key: 'sdfd', value:'sdfd' }
  }
  </code></pre>
  
  <p>I want to create another object by filtering the object above so I have something like.</p>
  
  <pre><code> {
      item1: { key: 'sdfd', value:'sdfd' },
      item3: { key: 'sdfd', value:'sdfd' }
   }
  </code></pre>
  
  <p>I am looking for a clean way to accomplish this using Es6, so spread operators are available to me.</p>