Add video.js vzaar example with protocol relative poster URL

We're hoping to be able to replicate the problem Matt W's reported with
the poster image not displaying on iOS devices[1].

[1]: https://www.pivotaltracker.com/story/show/71190278
Add video.js vzaar example with HTTPS poster URL

We're hoping to be able to replicate the problem Matt W's reported with
the poster image not displaying on iOS devices[1].

[1]: https://www.pivotaltracker.com/story/show/71190278