In case you want to update ckeditor be aware of:
    1. sometimes they decide to include some plugins directly inside ckeditor.js file
    2. you should set our "moto" skin as default one in config.js file
    3. you should update [lang] directory content and check plugins sprites (you can find them in [plugins] directory)

Attention!
We define property menu_groups in our ckeditor's config and set "white list" of properties which are allowed for context menu.
If you will add another plugin and this plugin needs context menu, be sure you add it's group in config property.
// https://github.com/ckeditor/ckeditor4/blob/8a12b041718e05eeffb62a931d95995ac72cbe22/plugins/menu/plugin.js#L609