title: Match route only if query param exists
body: <p>I want to match this route if url is <code>/test?x=5</code> and don't match if param x is not provided (<code>/test</code>):</p>
  
  <pre><code>stateProvider.state({
      name: 'someState',
      url: '/test?x',
      template: '&lt;div&gt;matched&lt;/div&gt;'
  });
  </code></pre>
  
  <p>This configuration does not work, route is matched in both cases. I need required <strong>query</strong> param.</p>
  
  <p>I was expecting clean solution like this:</p>
  
  <pre><code>stateProvider.state({
      name: 'someState',
      url: '/test',
      params: {
          x: {
              required: true
          }
      },
      template: '&lt;div&gt;matched&lt;/div&gt;'
  });
  </code></pre>