Youtube Channel ID από sacortesh

Features:
* Adds a button 'Copy ID' next to the channel name on any 'watch' page on youtube.
* Supports first load, or loading from dashboard/suggested videos.

Future developments:
* Add the button on the channel page.
* Add the button on the videos in the dashboard/suggested thumbnails.

Source code: https://github.com/sacortesh/ff-ext-youtube-id