Refactored BigVideo.show method and ...

separated playlist playback to BigVi...deo.showPlaylist

BigVideo.show now accepts source as an array of video object with parameters type and src, like videoJS natively accepts them.

Playlist playback is now accessible only via BigVideo.showPlaylist


NOTE:
* While this is not a breaking change, if users supplied only a video string to BigVideo.show it does change quite a bit of functionality
* The playlist functionality has been moved to its own function
* I haven't updated documentation pending feedback