bootstrap: initialize network configuration to an empty dict

Signed-off-by: Apollon Oikonomopoulos <apollon@noc.grnet.gr>

lib/bootstrap.py

@@ -527,6 +527,7 @@ def InitConfig(version, cluster_config, master_node_config,
                                    nodegroups=nodegroups,
                                    nodes=nodes,
                                    instances={},
+                                   networks={},
                                    serial_no=1,
                                    ctime=now, mtime=now)
   utils.WriteFile(cfg_file,