title: Change onHover colour of TextField Material-UI v1
body: <p>I m unable to change the onHover color of the TextField by overriding the classname. How can I do that? </p>
  
  <p>I'm using material UI v1: <a href="https://github.com/callemall/material-ui/tree/v1-beta" rel="noreferrer">https://github.com/callemall/material-ui/tree/v1-beta</a></p>