add es6 shim file

use Object.assign

client/es6-shims.js

@@ -0,0 +1 @@
+require('object.assign').shim();

client/index.js

@@ -1,3 +1,4 @@
+import unused from './es6-shims'; // eslint-disable-line
 import Rx from 'rx';
 import React from 'react';
 import Fetchr from 'fetchr';

common/app/app-stream.jsx

@@ -1,5 +1,4 @@
 import Rx from 'rx';
-import assign from 'object.assign';
 import { Router } from 'react-router';
 import App from './App.jsx';
 import AppCat from './Cat';
@@ -8,7 +7,7 @@ import childRoutes from './routes';
 
 const router$ = Rx.Observable.fromNodeCallback(Router.run, Router);
 
-const routes = assign({ components: App }, childRoutes);
+const routes = Object.assign({ components: App }, childRoutes);
 
 export default function app$(location) {
   return router$(routes, location)

common/app/routes/Hikes/flux/Actions.js

@@ -1,5 +1,4 @@
 import { Actions } from 'thundercats';
-import assign from 'object.assign';
 import debugFactory from 'debug';
 
 const debug = debugFactory('freecc:hikes:actions');
@@ -45,7 +44,7 @@ export default Actions({
                 dashedName,
                 oldState.currentHike
               );
-              return assign({}, oldState, { currentHike });
+              return Object.assign({}, oldState, { currentHike });
             }
           });
         }