change icon from object to string

client/client.go

@@ -47,7 +47,7 @@ type Message struct { // TODO combine with server.message
 	Priority   int
 	Tags       []string
 	Click      string
-	Icon       *Icon
+	Icon       string
 	Attachment *Attachment
 
 	// Additional fields
@@ -66,13 +66,6 @@ type Attachment struct {
 	Owner   string `json:"-"` // IP address of uploader, used for rate limiting
 }
 
-// Icon represents a message icon
-type Icon struct {
-	URL  string `json:"url"`
-	Type string `json:"type,omitempty"`
-	Size int64  `json:"size,omitempty"`
-}
-
 type subscription struct {
 	ID       string
 	topicURL string