title: ng-pattern only numbers in not required input
body: <p>I've an input text not required and I want to use a ng-pattern for only digits character, but when I submit the form, the input isn't valid. Why? </p>
  
  <pre><code>&lt;input type="text" ng-model="price" format="currency" ng-pattern="/^[0-9]*$/"&gt;
  </code></pre>
  
  <p>in jsfiddle, insert product without enter a price and submit:</p>
  
  <p><a href="http://jsfiddle.net/2f6qscrp/266/" rel="nofollow noreferrer">http://jsfiddle.net/2f6qscrp/266/</a></p>
  
  <p>ps: I cannont change the type of input!</p>