Add Support for Plex Media Server

I would be cool to see Plex support being added. Its like a normal streaming service on app.plex.tv and you just have to be signed in. I dont see it would technically not work.

If you want to have help developing it, i can give a plex share to the devs

Thanks a lot for your input. It seems like their player does not offer a way to be embedded in other websites which would be a prerequisite for an integration into Watch2Gether.