/*
Handler for the userMedia request
function _onUserMedia(engine, entity, callback, localMediaStream) {
      var source, analyser;

      source = this._context.createMediaStreamSource(localMediaStream);
      analyser = this._context.createAnalyser();
      source.connect(analyser);

      entity.addComponent(new Serpentity.Contrib.Components.Analyser({
        analyser : analyser
      }));

      entity.addComponent(new Serpentity.Contrib.Components.Configuration({
        config : {}
      }));

      engine.addEntity(entity);
      callback(entity);
    }