Add c2d machines to validMachineTypes (#195)

Author: glindstedt

rules/utils.go

@@ -119,6 +119,27 @@ var validMachineTypes = map[string]bool{
 	"c2-standard-16":   true,
 	"c2-standard-30":   true,
 	"c2-standard-60":   true,
+	"c2d-standard-2":   true,
+	"c2d-standard-4":   true,
+	"c2d-standard-8":   true,
+	"c2d-standard-16":  true,
+	"c2d-standard-32":  true,
+	"c2d-standard-56":  true,
+	"c2d-standard-112": true,
+	"c2d-highmem-2":    true,
+	"c2d-highmem-4":    true,
+	"c2d-highmem-8":    true,
+	"c2d-highmem-16":   true,
+	"c2d-highmem-32":   true,
+	"c2d-highmem-56":   true,
+	"c2d-highmem-112":  true,
+	"c2d-highcpu-2":    true,
+	"c2d-highcpu-4":    true,
+	"c2d-highcpu-8":    true,
+	"c2d-highcpu-16":   true,
+	"c2d-highcpu-32":   true,
+	"c2d-highcpu-56":   true,
+	"c2d-highcpu-112":  true,
 	"m2-ultramem-208":  true,
 	"m2-ultramem-416":  true,
 	"m2-megamem-416":   true,