Refactoring: variable names, adding tests and http constants

Signed-off-by: Alex Ellis <alexellis2@gmail.com>

gateway/tests/unmarshall_test.go

@@ -4,11 +4,9 @@
 package tests
 
 import (
-	"testing"
-
-	"io/ioutil"
-
 	"encoding/json"
+	"io/ioutil"
+	"testing"
 
 	"github.com/openfaas/faas/gateway/requests"
 )
@@ -19,21 +17,27 @@ func TestUnmarshallAlert(t *testing.T) {
 
 	var alert requests.PrometheusAlert
 	err := json.Unmarshal(file, &alert)
+
 	if err != nil {
 		t.Fatal(err)
 	}
+
 	if (len(alert.Status)) == 0 {
 		t.Fatal("No status read")
 	}
+
 	if (len(alert.Receiver)) == 0 {
 		t.Fatal("No status read")
 	}
+
 	if (len(alert.Alerts)) == 0 {
 		t.Fatal("No alerts read")
 	}
+
 	if (len(alert.Alerts[0].Labels.AlertName)) == 0 {
 		t.Fatal("No alerts name")
 	}
+
 	if (len(alert.Alerts[0].Labels.FunctionName)) == 0 {
 		t.Fatal("No function name read")
 	}