update README
p2pmanager: remove bemtvTracker embed parameter

Now, all variables defined on settings.js can be changed
in runtime. All that is needed is a hash called bemtv
on Clappr embed params, like this:

player = new Clappr.Player({
  source: 'http://cdn.bem.tv/stream/soccer5/playlist.m3u8',
  plugins: {playback: [P2PHLS], container: [P2PHLSStats]},
  watermark: "http://bem.tv/assets/watermark3.png",
  poster: 'http://cdn2.theinertia.com/wp-content/uploads/2012/05/Medina-Final.jpg',
  bemtv: {
    logging: true,
    maxUploadSlots: 5,
    tracker: 'http://your.tracker.here'
  }
});