Unconditioanlly adds "mlab" as value of Org field for v2 parsing (#189)

* Unconditioanlly adds "mlab" as value of Org field for v2 parsing

All v2 names are Org "mlab", so no reason to leave it blank

* Fixes unit tests for host package

* Adds comment about why Org="mlab" for v2 names

Author: nkinkade

host/host.go

@@ -138,7 +138,11 @@ func parseHostV2(f []string) (Name, error) {
 	if domain != "measurement-lab.org" {
 		return Name{}, fmt.Errorf("invalid domain: %#v", f)
 	}
+	// All V2 names represent machines that are managed by M-Lab, and join the
+	// M-Lab platform cluster. Unconditionally set Org to "mlab" rather than
+	// leaving it blank.
 	parts := Name{
+		Org:     "mlab",
 		Service: service,
 		Machine: machine,
 		Site:    site,

host/host_test.go

@@ -29,6 +29,7 @@ func TestName(t *testing.T) {
 			name:     "valid-v2",
 			hostname: "mlab1-lol01.mlab-sandbox.measurement-lab.org",
 			want: Name{
+				Org:     "mlab",
 				Machine: "mlab1",
 				Site:    "lol01",
 				Project: "mlab-sandbox",
@@ -40,6 +41,7 @@ func TestName(t *testing.T) {
 			name:     "valid-v2-with-suffix",
 			hostname: "mlab1-lol01.mlab-sandbox.measurement-lab.org-a9b8",
 			want: Name{
+				Org:     "mlab",
 				Machine: "mlab1",
 				Site:    "lol01",
 				Project: "mlab-sandbox",
@@ -52,6 +54,7 @@ func TestName(t *testing.T) {
 			name:     "valid-v2-with-service",
 			hostname: "ndt-mlab1-lol01.mlab-sandbox.measurement-lab.org",
 			want: Name{
+				Org:     "mlab",
 				Service: "ndt",
 				Machine: "mlab1",
 				Site:    "lol01",
@@ -64,6 +67,7 @@ func TestName(t *testing.T) {
 			name:     "valid-v2-with-service-and-suffix",
 			hostname: "ndt-mlab1-lol01.mlab-sandbox.measurement-lab.org-a9b8",
 			want: Name{
+				Org:     "mlab",
 				Service: "ndt",
 				Machine: "mlab1",
 				Site:    "lol01",
@@ -92,6 +96,7 @@ func TestName(t *testing.T) {
 			name:     "valid-v2-bmc",
 			hostname: "mlab1d-lol01.mlab-sandbox.measurement-lab.org",
 			want: Name{
+				Org:     "mlab",
 				Machine: "mlab1d",
 				Site:    "lol01",
 				Project: "mlab-sandbox",