title: Angular.js: Set form fields "dirty" upon submission
body: <p>How can I make a form input to become dirty as the form is submitted?</p>
  
  <p>This is needed so that the input fields with an $error can be </p>
  
  <p>Example:</p>
  
  <pre><code>    name: &lt;input    type="text"
                      ng-model="user.name" 
                      ng-model-options="{ updateOn: 'blur' }"
                      name="uName"
                      required /&gt;&lt;br/&gt;
  </code></pre>
  
  <p>As the form is submitted, I want this field - if left blank - to be rendered using the "invalid &amp; dirty" style:</p>
  
  <pre><code>    .css-form input.ng-invalid.ng-dirty {
  
          background-color: #FA787E;
      }
  </code></pre>