Add jsonSerialize method to RelationalEntity

Signed-off-by: Julius Haertl <jus@bitgrid.net>

lib/Db/Label.php

@@ -33,16 +33,8 @@ class Label extends RelationalEntity implements JsonSerializable {
 	protected $color;
 	protected $boardId;
 	protected $cardId;
+	
 	public function __construct() {
 		$this->addType('id', 'integer');
 	}
-	public function jsonSerialize() {
-		return [
-			'id' => $this->id,
-			'title' => $this->title,
-			'boardId' => $this->boardId,
-			'cardId' => $this->cardId,
-			'color' => $this->color,
-		];
-	}
 }