Merge branch 'v4.0.0-dev' of https://github.com/AllenFang/react-bootstrap-table into v4.0.0-dev

Author: AllenFang

src/ExpandRowHeaderColumn.js

@@ -1,4 +1,5 @@
-import React, { Component, PropTypes } from 'react';
+import React, { Component } from 'react';
+import PropTypes from 'prop-types';
 
 class ExpandRowHeaderColumn extends Component {