release: stable-4857

* a81ad734 prosody: add support for lobby
* baed6055 web: fix removing closed captions button if transcription is enabled
* edecacd0 etherpad: add ability to use a external server
* a7563d4f jvb: use JVB_TCP_PORT for exposing the port
* b235ea12 prosody: disable s2s module
* 1d428a84 prosody: use a 2-stage build
* 613c26c1 misc: working on latest
* 4d72ee37 release: stable-4627-1
* 22b7063e examples: update Traefik v1 example
* 1381b08a prosody: fix installing dependdencies
* 2900c117 misc: add extra line to tag message
* c57a84b2 misc: working on latest