Switch prerolls between content changes support

[pcting]

• Vast.getContent No Longer Accepts Arguments Fix
• Added getter/setter player.vast.url() and player.vast.skip() functions so that you can change the settings between content changes so you can do something like this:

function changeVideo(player, video, adTag) {
  player.vast.url(adTag);
  player.vast.skip(parseInt(Math.random() * 5));
  player.poster(video.poster);
  player.src(video.src);
}

• The package is currently registered at bower.io as "videojs-vast". I've renamed the name in the bower.json file to match this.

[coveralls]

Coverage decreased (-2.43%) to 62.73% when pulling c15d3f7 on pcting:master into 565e0ac on theonion:master.

[pcting]

Another thing to note is that I'm working with video.js 4.11.4 and videojs-contrib-ads master; I'm not sure if this will break with older dependencies.

[vforgione]

can you please provide a little more detail on this? we're using this with video.js#4.12.5 in production on at least one site without issue.