Update to use prop-types module in components.

src/components/modals/Modal.jsx

@@ -1,12 +1,13 @@
 import React from 'react'
+import PropTypes from 'prop-types'
 import CloseIcon from 'react-icons/lib/md/close'
 import Overlay from './Overlay'
 
 class Modal extends React.Component {
   static propTypes = {
-    isOpen: React.PropTypes.bool.isRequired,
-    title: React.PropTypes.string.isRequired,
-    onOpenToggle: React.PropTypes.func.isRequired,
+    isOpen: PropTypes.bool.isRequired,
+    title: PropTypes.string.isRequired,
+    onOpenToggle: PropTypes.func.isRequired,
   }
 
   render() {