Improve YouTube integration#727

Add all the missing parts of video uploading. Like:

-Thumbnail
-Tags
-Playlist
-Audience
-Category
-Comments (on/off/fileter)
etc.

plus, would be nice to have keyword tool aswell.

Thank you for the feedback.

P.S. You can already select a thumbnail from the ones that we automatically generate, or upload a custom one (use the icons below the video thumbnail when you upload one in Publer)