title: How to change the format of a reactjs material ui date picker
body: <p>I just need a super-simple picker where someone can type in the date and/or pick it from a calendar.   The material-ui picker meets my needs for that.</p>
  
  <p>However, it shows the date in MM/DD/YYYY   (Even though it's internally stored YYYY-MM-DD if you spit out the value of the TextField)</p>
  
  <p>You can see this on the demo here: <a href="https://material-ui.com/demos/pickers/" rel="nofollow noreferrer">https://material-ui.com/demos/pickers/</a></p>
  
  <p>I'd like to have the displayed date be YYYY/MM/DD (or YYYY-MM-DD).</p>
  
  <p>I've tried building a formatDate function, as outlined in many other questions on this and some older docs... but that results in me getting a <code>React does not recognize the</code>formatDate<code>prop on a DOM element. If you intentionally want it to appear in the DOM as a custom attribute, spell it as lowercase</code>formatdate<code>instead.</code> error.</p>
  
  <p>This also came up in git discussions and the topic was closed without any real resolution: <a href="https://github.com/mui-org/material-ui/issues/10251" rel="nofollow noreferrer">https://github.com/mui-org/material-ui/issues/10251</a></p>
  
  <p>Surely there is a way to do this...  help?</p>