Merge pull request digitalocean#104 from chaseadamsio/cleanup-createI…

…mageMarshalJSON

organizes dropletCreateImage MarshalJSON declaration

droplets.go

@@ -147,6 +147,16 @@ type DropletCreateImage struct {
 	Slug string
 }
 
+// MarshalJSON returns either the slug or id of the image. It returns the id
+// if the slug is empty.
+func (d DropletCreateImage) MarshalJSON() ([]byte, error) {
+	if d.Slug != "" {
+		return json.Marshal(d.Slug)
+	}
+
+	return json.Marshal(d.ID)
+}
+
 // DropletCreateVolume identifies a volume to attach for the create request. It
 // prefers Name over ID,
 type DropletCreateVolume struct {
@@ -168,16 +178,6 @@ func (d DropletCreateVolume) MarshalJSON() ([]byte, error) {
 	}{ID: d.ID})
 }
 
-// MarshalJSON returns either the slug or id of the image. It returns the id
-// if the slug is empty.
-func (d DropletCreateImage) MarshalJSON() ([]byte, error) {
-	if d.Slug != "" {
-		return json.Marshal(d.Slug)
-	}
-
-	return json.Marshal(d.ID)
-}
-
 // DropletCreateSSHKey identifies a SSH Key for the create request. It prefers fingerprint over ID.
 type DropletCreateSSHKey struct {
 	ID          int