Develop cherry pick

Cherry picked a few commits from develop that should be included in the 0.19.1 release:

• aa5fd6b2 Fix websockets reverse proxy
• bc677793 Fix French translation for "Start radio"
• 4ab490eb (origin/listenings-filter, listenings-filter) Added username and domain filter on /history/listenings endpoint
• 3814c110 Added some documentation about translations lifecycle
• 7bcf896f Added fix + changelog fragment for #838 (closed)
• d530aca4 Resolve "Add documentation for resolver conf"