title: Angular, material form only say field is required after submit attempt
body: <p>I a building my apps login form with angular-material and  am trying to use it a bit differently than the examples on their page. I just want the required fields to only yell at me if the user tries to submit without filling a field out. Maybe disable the button too? Regardless, if the user only fills one field out and presses enter, I would like it to show that "this is required". Right now it just shows it all the time until you fill it out</p>
  
  <p>Here is what I have : <a href="https://jsfiddle.net/5b1tsm2a/6/">https://jsfiddle.net/5b1tsm2a/6/</a></p>
  
  <p>I am trying the code from their example page like so -</p>
  
  <pre><code>  &lt;form ng-submit="authenticate()" name="loginForm"&gt;
          &lt;md-input-container&gt;
              &lt;label&gt;Username&lt;/label&gt;
              &lt;input name="name" reauired ng-model="loginInfo.username"&gt;
              &lt;div ng-messages="projectForm.description.$error"&gt;
                  &lt;div ng-message="required"&gt;This is required.&lt;/div&gt;
              &lt;/div&gt;
          &lt;/md-input-container&gt;
  
          &lt;md-input-container&gt;
              &lt;label&gt;Password&lt;/label&gt;
              &lt;input name="password" reauired type="password" ng-model="loginInfo.password"&gt;
              &lt;div ng-messages="projectForm.description.$error"&gt;
                  &lt;div ng-message="required"&gt;This is required.&lt;/div&gt;
              &lt;/div&gt;
          &lt;/md-input-container&gt;
  
          &lt;md-button ng-click="authenticate()" class="md-primary btn btn-primary"&gt;Login&lt;/md-button&gt;
      &lt;/form&gt;
  </code></pre>
  
  <p>So I'm using the required logic with the ng-messages below it. I would only like that to show if they have tried to submit without filling out anything. Thanks!</p>