[doc] Freetube browser integration, extension

[ghost]

You can add this tutorial to README:
http://www.newline.blog/posts/freetube/

[LoganJFisher]

This works great! Thank you.

One question: When clicking a video, it loads YouTube's "Connect to the internet - You're offline. Check your connection" page in Firefox. Is there any way to make it stay on the YouTube home page instead? Having to hit "back" isn't a big deal, but it would be convenient to not have to.