title: how to use css classes inside angular formly
body: <p>I am using angular formly. I read the documentation,but they didn't mention how to apply css classes from options.
  I am trying to apply kendo ui classes to form fields but of no use.
  Can anyone help me?</p>
  
  <p>here is my jsbin</p>
  
  <p><a href="http://jsbin.com/golehimize/edit?html,output" rel="nofollow">http://jsbin.com/golehimize/edit?html,output</a></p>