fix a bug after install websosket
add a web socket server
the user can be group talking．the show page in the 0.0.0.0:3000/users after you click the toTalk
button.
updated UI
Apply Model and concept changes to WebRTC implementation:
- participant information now contains:
  - user token
  - client ID
  - both combined to identifier
  - and name

basic error handling -> use only audio, when no video is available.

minor adjustments in view.
removed scaffolds.css.scss -> destroys layout
add datepicker
Merge branch 'master' into timepicker
Merge branch 'timepicker'