title: Change format of md-datepicker in Angular Material with momentjs
body: <p>Angular material introduced a new date picker component found <a href="https://material.angularjs.org/HEAD/#/demo/material.components.datepicker">here</a>.</p>
  
  <p>I want the date returned by this component to be in the format <em>yyy-mm-dd</em> but I am not sure how is this done. By searching I found that <code>$mdDateLocaleProvider</code> can be used, but I could not find an example of using it.</p>
  
  <p>Can someone show me a working example of formatting the date returned by <code>md-datepicker</code>?</p>