fix: Fix imports to play nicely with rollup (#530)

src/CSSTransition.js

@@ -1,4 +1,4 @@
-import * as PropTypes from 'prop-types';
+import PropTypes from 'prop-types';
 import addOneClass from 'dom-helpers/class/addClass';
 
 import removeOneClass from 'dom-helpers/class/removeClass';

src/ReplaceTransition.js

@@ -1,6 +1,6 @@
 import PropTypes from 'prop-types';
 import React from 'react';
-import { findDOMNode } from 'react-dom'
+import ReactDOM from 'react-dom'
 import TransitionGroup from './TransitionGroup';
 
 /**
@@ -28,7 +28,7 @@ class ReplaceTransition extends React.Component {
     const child = React.Children.toArray(children)[idx];
 
     if (child.props[handler]) child.props[handler](...originalArgs)
-    if (this.props[handler]) this.props[handler](findDOMNode(this))
+    if (this.props[handler]) this.props[handler](ReactDOM.findDOMNode(this))
   }
 
   render() {

src/Transition.js

@@ -1,4 +1,4 @@
-import * as PropTypes from 'prop-types'
+import PropTypes from 'prop-types'
 import React from 'react'
 import ReactDOM from 'react-dom'