Remove all references to React.PropTypes.

Fixes #101.

Author: leMaik

src/ChipInput.js

@@ -109,7 +109,7 @@ const defaultChipRenderer = ({ value, text, isFocused, isDisabled, handleClick,
 
 class ChipInput extends React.Component {
   static contextTypes = {
-    muiTheme: React.PropTypes.object.isRequired,
+    muiTheme: PropTypes.object.isRequired,
   };
 
   state = {

stories/ControlledChipInput.js

@@ -1,4 +1,5 @@
 import React from 'react'
+import PropTypes from 'prop-types'
 import ChipInput from '../src/ChipInput'
 
 class ControlledChipInput extends React.Component {
@@ -42,7 +43,7 @@ class ControlledChipInput extends React.Component {
 }
 
 ControlledChipInput.propTypes = {
-  addOnBlur: React.PropTypes.bool
+  addOnBlur: PropTypes.bool
 }
 
 export default ControlledChipInput