title: Missing step attribute error message in input
body: <p>Angular js does provide a validation for several html5 introduced attributes of an input, like <code>min</code> or <code>required</code>including the . </p>
  
  <pre><code>&lt;input type="number" name="input1" id="input1" min="0" 
          ng-model="$ctrl.input1"ng-required /&gt;
  &lt;div ng-messages="formname.input1.$error" class="em-messages"&gt;
      &lt;div ng-message="required"&gt;This value is required&lt;/div&gt;
      &lt;div ng-message="min"&gt;You must not use negative values&lt;/div&gt;
  &lt;/div&gt;
  </code></pre>
  
  <p>For the <code>step</code> attribute such a validation is working, but no error message can be displayed the material way by default, so what's the easiest way to implement it (for example for <code>step="0.001"</code>?</p>
  
  <pre><code>&lt;input type="number" name="input1" id="input1" min="0" step="0.001"
          ng-model="$ctrl.input1"ng-required /&gt;
  &lt;div ng-messages="formname.input1.$error" class="em-messages"&gt;
      &lt;div ng-message="required"&gt;This value is required&lt;/div&gt;
      &lt;div ng-message="min"&gt;You must not use negative values&lt;/div&gt;
      &lt;div ng-message="step"&gt;You can work with 0.001 steps&lt;/div&gt;
  &lt;/div&gt;
  </code></pre>