style: sort imports in compute node modules

gns3server/compute/dynamips/nodes/frame_relay_switch.py

@@ -20,13 +20,12 @@ http://github.com/GNS3/dynamips/blob/master/README.hypervisor#L642
 """
 
 import asyncio
-
-from .device import Device
-from ..nios.nio_udp import NIOUDP
-from ..dynamips_error import DynamipsError
-
 import logging
 
+from ..dynamips_error import DynamipsError
+from ..nios.nio_udp import NIOUDP
+from .device import Device
+
 log = logging.getLogger(__name__)