Revert "Update video.js references to 4.11.2 and ads-contrib to 0.5.0."
Merge pull request #38 from googleads/revert-36-vjs_11

Revert "Update video.js references to 4.11.2 and ads-contrib to 0.5.0."
Merge branch 'master' into gh-pages
Merge branch 'gh-pages' of github.com:googleads/videojs-ima into gh-pages
Updated video.hs to 4.7.2 and contrib-ads to 0.5.0.
Merge branch 'vjs_11' into gh-pages
testing vjs4.7.2 and ads 0.5.0