use correct prop-types package

Author: jscottsmith

package.json

@@ -28,9 +28,9 @@
   "author": "J Scott Smith",
   "license": "ISC",
   "dependencies": {
+    "prop-types": "^15.5.10",
     "react": "^15.4.2",
-    "react-dom": "^15.4.2",
-    "react-proptypes": "^1.0.0"
+    "react-dom": "^15.4.2"
   },
   "devDependencies": {
     "babel-cli": "^6.24.1",

src/components/Parallax.js

@@ -1,5 +1,5 @@
 import React, { Component } from 'react';
-import PropTypes from 'react-proptypes';
+import PropTypes from 'prop-types';
 import { offsetMin, offsetMax } from '../utils/propValidation';
 
 export default class Parallax extends Component {