BUILDBOT: Add keepalive pings

This will avoid closing by the reverse proxy

buildbot-config/config.py.example

@@ -85,6 +85,9 @@ buildbot_url = "https://buildbot.scummvm.org/"
 # Retention time for data (in weeks)
 data_retention_weeks = 4
 
+# Ping interval to keep websocket alive
+ws_ping_interval = 0
+
 change_horizon = 1000
 
 # URL used to download daily builds

buildbot-config/ui.py

@@ -87,6 +87,9 @@ try:
 except TypeError:
     www['port'] = "tcp:{0}".format(config.www_port)
 
+if hasattr(config, 'ws_ping_interval'):
+    www['ws_ping_interval'] = config.ws_ping_interval
+
 if hasattr(config, 'irc') and config.irc:
     services.append(reporters.IRC(
         host=config.irc['server'],