OP#830 add bollean for toggling using lan server

templates/chrony.conf.erb

@@ -63,7 +63,13 @@ log <%= @cy_loginfo %>
 
 <% if @fqdn != @cy_server_fqdn -%>
 # This is a time client configuration file
+<% if @cy_use_lan_server -%>
 server <%= @cy_server_fqdn %> iburst
+<% else -%>
+# Use public servers from the pool.ntp.org project.
+<% @cy_conf_servers.each do |this_server| -%>
+server <%= this_server %> iburst
+<% end -%>
 
 # Use NTP servers from DHCP.
 sourcedir /run/chrony-dhcp