feat: add's new client entry point

use `import { render, wrapRootEpic } from 'react-redux-epic/client';` on the client side to prevent
bundling unnecessary files

client.js

@@ -0,0 +1,4 @@
+module.exports = {
+  render: require('./lib/render.js').default,
+  wrapRootEpic: function(f) { return f; }
+};

src/render.js

@@ -1,4 +1,4 @@
-import ReactDOM from 'react-dom';
+import { render as _render, unmountComponentAtNode } from 'react-dom';
 import { Observable } from 'rxjs/Observable';
 import { Subscription } from 'rxjs/Subscription';
 
@@ -10,15 +10,15 @@ import { Subscription } from 'rxjs/Subscription';
 export default function render(Component, DOMContainer) {
   return Observable.create(observer => {
     try {
-      ReactDOM.render(Component, DOMContainer, function() {
+      _render(Component, DOMContainer, function() {
         observer.next(this);
       });
     } catch (e) {
       return observer.error(e);
     }
 
     return new Subscription(() => {
-      return ReactDOM.unmountComponentAtNode(DOMContainer);
+      return unmountComponentAtNode(DOMContainer);
     });
   });
 }