fix(videojs.hotkeys.js): Copied extend method that was being used by other videojs tech to be consistent.
fix(videojs.hotkeys.js): Copied extend method that was being used by other videojs tech to be consistent.

Fix invalid option overrwriting.

previously:

`var enableMute = false || true // always true`

Also, formatting.

ctd1500/videojs-hotkeys,ctd1500/videojs-hotkeys