Example site layout updates.

Cherry-pick commit: https://github.com/ajbogh/webRTC.io/commit/cab9299a9148665c4933fd720db6fa56f175694e

Git shows 82 commits for some reason, not sure why. Feel free to cherry-pick for safety.

In the above commit I changed the example site layout. The remote videos are laid out on the left in a similar row/column format as before. The subdivide function has been fixed and the remote videos have been muted to prevent echoing in local testing. The audio can be unmuted by right-clicking the video.

The buttons are now on the right with the local video below them. The chat section is below the local video, taking up the remainder of the space. The toggle chat button is removed but it can be added back in at a later date.

Removing a remote video will now cause a subdivide task to execute once more.

The background has been changed to black to bring out more of the video.