fix(src): switch to findDOMNode from "react-dom"

* Original commit: d177b45
* Original author @zillding
* Closes #132
* Ref #129

src/GoogleMap.js

@@ -2,9 +2,12 @@ import {
   default as React,
   PropTypes,
   Component,
-  findDOMNode,
 } from "react";
 
+import {
+  findDOMNode,
+} from "react-dom";
+
 import {
   default as GoogleMapHolder,
   mapDefaultPropTypes,
@@ -52,7 +55,7 @@ export default class GoogleMap extends Component {
   //
   // Public APIs - Use this carefully
   // See discussion in https://github.com/tomchentw/react-google-maps/issues/62
-  // 
+  //
   // https://developers.google.com/maps/documentation/javascript/3.exp/reference#Map
   //
   // [].map.call($0.querySelectorAll("tr>td>code"), function(it){ return it.textContent; }).filter(function(it){ return !it.match(/^get/) && !it.match(/^set/) && !it.match(/Map$/); })