ircbot: flush channel logging continuously

We've seen evidence of channel logs not getting flushed for very
long timespans (as much as a day on some channels), so adjust the
configuration to flush channel log files immediately after each line
is written. We don't log *that* many channels and our discussion
volume isn't so high that this is likely to cause I/O performance
issues for the server.

Change-Id: Ia56d3d8c21c48d8ed6ba2466c914e0c20a6192c3

playbooks/roles/limnoria/templates/limnoria.config.j2

@@ -1629,7 +1629,7 @@ supybot.plugins.ChannelLogger.enable: True
 #
 # Default value: False
 ###
-supybot.plugins.ChannelLogger.flushImmediately: False
+supybot.plugins.ChannelLogger.flushImmediately: True
 
 ###
 # Determines whether formatting characters (such as bolding, color,