Fixed pathing of TinyMCE icon through addition of "wp_localize_script" c...

Hey there!

I use a custom location for my WordPress plugins (both not wp-content and within mu-plugins). This was causing the custom TinyMCE icon to break for the video embeds through your application (doh!). I added a quick localization fix to your base administrative class (admin/class-advanced-responsive-video-embedder-admin.php) and updated your TinyMCE plugin (admin/assets/js/mce-plugin.js) to match.

Tested things and it looks to be AOK - let me know if you would like any more details!

Thanks for such a great piece of code =)

Cheers,
- folkhack