Add extra plugins to CKEditor.

Hello everyone.
I'm trying to add an extra plugin in CKEditor using the following code ...
In /mod/ckeditor/views/default/js/elgg/ckeditor/config.js

define(function(require) {
    var elgg = require('elgg');
    var $ = require('jquery');

    return {
        toolbar: [['Bold', 'Italic', 'Underline', 'RemoveFormat'], ['Strike', 'NumberedList', 'BulletedList', 'Undo', 'Redo', 'Link', 'Unlink', 'Image', 'Blockquote', 'Paste', 'PasteFromWord','ckwebspeech', 'Maximize']],
        removeButtons: 'Subscript,Superscript', // To have Underline back
        allowedContent: true,
        baseHref: elgg.config.wwwroot,
        removePlugins: 'contextmenu,tabletools,resize',
        extraPlugins: 'ckwebspeech',      //   Line added
        defaultLanguage: 'en',
        language: elgg.config.language,
        skin: 'moono',
        uiColor: '#EEEEEE',
        contentsCss: elgg.get_simplecache_url('css', 'elgg/wysiwyg.css'),
        disableNativeSpellChecker: false,
        disableNativeTableHandles: false,
        removeDialogTabs: 'image:advanced;image:Link;link:advanced;link:target',
        autoGrow_maxHeight: $(window).height() - 100

But changes do not appear.
Am I doing it the right way?
Is there any other configuration file for ckeditor?