v0.5.0

This is a minor release of this package. We're one more step closer to stable version. Following are changes. For details you can look at the source yourself or look up our documentation.

+ add license
+ add serveral options
+ reconstruct way to play for more supports in the future
+ now you can set volume
+ add getVideoData to youtube util
+ YoutubeVideoData now extends BaseYoutubeVideoData
- remove ffmpeg-static dependency