3rd beta version

Changelog

• Minor refactors
  • Remove unnecessary argument from function connect of MillicastSignaling.
  • Throw exception when call onUserCount when MillicastStreamEvents is not constructed via builder function.
  • Transpile ES module to add support from ES6.
• Check MediaStream tracks
  • Add check that media stream received from user contains no more than 1 audio and video track.
  • User could supply one media stream or an array of media stream tracks.
• Replace active track
  • Now you can switch an audio or video track to another when you are broadcasting.
• Unit testing
  • Tests with Jest Cucumber.
  • Add MillicastDirector unit tests.