Allow unspecified protocol on exposed port in kube backend

Signed-off-by: Michael Irwin <mikesir87@gmail.com>

The Compose spec doesn't provide a default value, but the code
was defaulting to TCP in the service protocol, just not in the
name. If no protocol was specified, it would cause an invalid
service name (eg, "80-")

kube/resources/kube.go

@@ -92,12 +92,13 @@ func mapToService(project *types.Project, service types.ServiceConfig) *core.Ser
 		if p.Published != 0 {
 			serviceType = core.ServiceTypeLoadBalancer
 		}
+		protocol := toProtocol(p.Protocol)
 		ports = append(ports,
 			core.ServicePort{
-				Name:       fmt.Sprintf("%d-%s", p.Published, strings.ToLower(p.Protocol)),
+				Name:       fmt.Sprintf("%d-%s", p.Published, strings.ToLower(string(protocol))),
 				Port:       int32(p.Published),
 				TargetPort: intstr.FromInt(int(p.Target)),
-				Protocol:   toProtocol(p.Protocol),
+				Protocol:   protocol,
 			})
 	}
 	if len(ports) == 0 { // headless service