Allow Chaining of config.setup for Editor Init

This allows user plugin configuration without having to hook refs, etc.
Still add custom event proxying and initial content, but allow definition of a setup callback that is invoked after wrapper initialization. This allows configuration similar to the official TinyMCE examples (such as http://www.tinymce.com/tryit/3_x/custom_toolbar_button.php)

Author: apelican

lib/components/TinyMCE.js

@@ -99,6 +99,9 @@ const TinyMCE = React.createClass({
     // hide the textarea that is me so that no one sees it
     findDOMNode(this).style.hidden = 'hidden';
 
+    var setupCallback = config.setup;
+    var hasSetupCallback = (typeof setupCallback === 'function');
+
     config.selector = '#' + this.id;
     config.setup = (editor) => {
       EVENTS.forEach((event, index) => {
@@ -116,6 +119,9 @@ const TinyMCE = React.createClass({
           editor.setContent(content);
         });
       }
+      if(hasSetupCallback) {
+        setupCallback(editor);
+      }
     };
 
     tinymce.init(config);