Adds support for dm deployed-instances <type>:<version>.

When you deploy with <type>:<version>, the type actually seen by DM is
the template URL. While the template URL still shows up as the type when
performing a "dm deployed-types", this at least lets you look for
instances of a known type.

Refactoring the type URL code in client a bit.

Refactoring getTypeUrl.

dm/dm.go

@@ -110,10 +110,7 @@ func main() {
 		fmt.Printf("Templates:\n")
 		for _, t := range templates {
 			fmt.Printf("%s:%s\n", t.Name, t.Version)
-			downloadURL, err := git.GetURL(t)
-			if err != nil {
-				log.Printf("Failed to get download URL for template %s:%s", t.Name, t.Version)
-			}
+			downloadURL := getDownloadUrl(t)
 
 			fmt.Printf("\tdownload URL: %s\n", downloadURL)
 		}
@@ -159,8 +156,9 @@ func main() {
 			usage()
 		}
 
-		path := fmt.Sprintf("types/%s/instances", url.QueryEscape(args[1]))
-		action := fmt.Sprintf("list deployed instances of type %s", args[1])
+		tUrl := getTypeUrl(args[1])
+		path := fmt.Sprintf("types/%s/instances", url.QueryEscape(tUrl))
+		action := fmt.Sprintf("list deployed instances of type %s", tUrl)
 		callService(path, "GET", action, nil)
 	default:
 		usage()
@@ -204,28 +202,38 @@ func describeType(args []string) {
 		usage()
 	}
 
-	var tUrl string
+	tUrl := getTypeUrl(args[1])
+	schemaUrl := tUrl + ".schema"
+	fmt.Println(callHttp(schemaUrl, "GET", "get schema for type ("+tUrl+")", nil))
+}
 
-	if strings.HasPrefix(args[1], "http://") || strings.HasPrefix(args[1], "https://") {
+func getTypeUrl(tName string) string {
+	if isHttp(tName) {
 		// User can pass raw URL to template.
-		tUrl = args[1]
-	} else {
-		// User can pass registry type.
-		t := getRegistryType(args[1])
-		if t == nil {
-			log.Fatalf("Invalid type name, must be in the form \"<type-name>:<version>\": %s", args[1])
-		}
+		return tName
+	}
 
-		git := getGitRegistry()
-		url, err := git.GetURL(*t)
-		if err != nil {
-			log.Fatalf("Failed to fetch type information for %s: %s", args[1], err)
-		}
-		tUrl = url
+	// User can pass registry type.
+	t := getRegistryType(tName)
+	if t == nil {
+		log.Fatalf("Invalid type name, must be in the form \"<type-name>:<version>\": %s", tName)
 	}
 
-	schemaUrl := tUrl + ".schema"
-	fmt.Println(callHttp(schemaUrl, "GET", "get schema for type ("+tUrl+")", nil))
+	return getDownloadUrl(*t)
+}
+
+func getDownloadUrl(t registry.Type) string {
+	git := getGitRegistry()
+	url, err := git.GetURL(t)
+	if err != nil {
+		log.Fatalf("Failed to fetch type information for \"%s:%s\": %s", t.Name, t.Version, err)
+	}
+
+	return url
+}
+
+func isHttp(t string) bool {
+	return strings.HasPrefix(t, "http://") || strings.HasPrefix(t, "https://")
 }
 
 func loadTemplate(args []string) *expander.Template {
@@ -267,11 +275,7 @@ func getRegistryType(fullType string) *registry.Type {
 }
 
 func buildTemplateFromType(t registry.Type) *expander.Template {
-	git := getGitRegistry()
-	downloadURL, err := git.GetURL(t)
-	if err != nil {
-		log.Fatalf("Failed to get download URL for type %s:%s\n%s\n", t.Name, t.Version, err)
-	}
+	downloadURL := getDownloadUrl(t)
 
 	props := make(map[string]interface{})
 	if *properties != "" {