Add public variable player.ads.lastSrc to allow other plugins to change the source without triggering a contentupdate and an ad.
Move lastSrc comment to match previous commit
Merge branch 'master' of github.com:nhjm449/videojs-contrib-ads into nhjm449-master

Conflicts:
	src/videojs.ads.js
Rename lastSrc to currentSrc
Change the name of a property so it is more consistent with the `contentupdate` event. Add documentation and a test case.
Merge pull request #43 from videojs/feature/contentSrc

Feature/content src