SeekHandle content

I wanted to use the SeekHandle to show the current time but as far as I could tell it only contained static content, I made this change to allow the content to be updated.

Is this its intended purpose or am I playing with something that has another a different job?
Update progress-control.js
Merge branch 'patch-1' of git://github.com/MrAvenger/video.js into MrAvenger-patch-1
Switch this.content references to use the standard this.contentEl_

Also cleaned up some comments and formatting.
Updated changelog