fix #68 Use prop-types package

Author: charlesponti

package.json

@@ -28,6 +28,7 @@
     "input"
   ],
   "dependencies": {
+    "prop-types": "^15.5.8",
     "select2": "^4.0.0",
     "shallow-equal-fuzzy": "^0.0.2"
   },

src/components/Select2.js

@@ -1,4 +1,5 @@
-import React, { Component, PropTypes } from 'react';
+import React, { Component } from 'react';
+import PropTypes from 'prop-types';
 import ReactDOM from 'react-dom';
 import shallowEqualFuzzy from 'shallow-equal-fuzzy';
 import $ from 'jquery';