title: Angular form is $valid when all inputs are blank, why?
body: <p>My form is showing up as valid even though all of my input fields are blank.
  I have the required keyword in the input fields.</p>
  
  <pre><code>&lt;!DOCTYPE html&gt;
  &lt;html ng-app="myApp"&gt;
    &lt;head&gt;
      &lt;link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/materialize/0.96.1/css/materialize.min.css"&gt;
      &lt;script src="http://ajax.googleapis.com/ajax/libs/jquery/1.11.2/jquery.min.js"&gt;&lt;/script&gt;
      &lt;script type="text/javascript" src="/components/angular/angular.min.js"&gt;&lt;/script&gt;
      &lt;script type="text/javascript" src="/js/app.js"&gt;&lt;/script&gt;
    &lt;/head&gt;
  
    &lt;body&gt;
      &lt;main&gt;
        &lt;div class="container"&gt;
          &lt;div class="row"&gt;
            &lt;section ng-controller="LogInController as loginCtrl"&gt;
              &lt;form name="signUpForm" action="/createuser" method="POST" novalidate&gt;
                &lt;fieldset&gt;
                &lt;div class="field input-field"&gt;
                  Email &lt;br /&gt;
                  &lt;input type="email" name="email" required /&gt;
                &lt;/div&gt;
  
                &lt;div class="field input-field"&gt;
                  Password &lt;br /&gt;
                  &lt;input type="password" name="password" required /&gt;
                &lt;/div&gt;
  
                &lt;div class="field input-field"&gt;
                  Confirm Password &lt;br /&gt;
                  &lt;input type="password" name="confirmation" required /&gt;
                &lt;/div&gt;
  
                !! -- Form valid? {{signUpForm.$valid}} -- !!
  
                &lt;div class="actions"&gt;
                  &lt;input type="submit" value="Sign Up" /&gt;
                &lt;/div&gt;
                &lt;/fieldset&gt;
              &lt;/form&gt;
            &lt;/section&gt;
          &lt;/div&gt;
        &lt;/div&gt;
      &lt;/main&gt;
    &lt;/body&gt;
  &lt;/html&gt;
  </code></pre>
  
  <p>Loading this in the browser results in !! -- Form valid? true -- !!
  I thought angular knows that the required tag makes a blank field invalid?</p>