Adding missing (recent) versions of video-js

I noticed this library was locked in at video-js v4.1.0. For our uses, that version has a pretty nasty bug that causes problems with dispatching `timeupdate` events — https://github.com/videojs/video.js/issues/620 — and numerous other versions have popped up since then.

I've added each subsequent version incrementally as a new commit to this library, so that if others need to lock in a specific version of video-js, they can do so.

In my fork, I've tagged each commit with the particular version number of video-js as well. GitHub PRs don't allow for tags to be in the PR, so these won't carry over. If you don't want to go through the trouble of tagging each commit, and subsequently building and pushing those versions to rubygems.org, and *you'd like those* to be on rubygems.org, you could give me push access to this repo and I can take care of it. If not, certainly no biggie there (and no offense taken!); just a convenience.

Thanks for hosting this library, @seanbehan!