Merge branch '2.1' into 2.2

# Conflicts:
#	gns3server/compute/iou/iou_vm.py
#	gns3server/compute/virtualbox/virtualbox_vm.py
#	gns3server/compute/vmware/vmware_vm.py

gns3server/ubridge/hypervisor.py

@@ -62,6 +62,7 @@ class Hypervisor(UBridgeHypervisor):
                     af, socktype, proto, _, sa = res
                     # let the OS find an unused port for the uBridge hypervisor
                     with socket.socket(af, socktype, proto) as sock:
+                        sock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
                         sock.bind(sa)
                         port = sock.getsockname()[1]
                         break