* feat(realtime-chat): add Pusher library to the server
* feat(realtime-chat): only for private groups
* feat(realtime-chat): add authentication endpoint for Pusher
* feat(realtime-chat): client proof of concept
* fix typo in apidoc
* feat(realtime-chat): redo authentication and write integration tests
* remove firebase code
* fix client side tests
* fix line ending in bower.json
* feat(realtime chat): use presence channels for parties, send events & disconnect clients if user leaves or is removed from party, automatically update UI
* pusher: enable all events in the background
* fix pusher integration tests
