Do not list file starting with a . in upload handler

gns3server/handlers/upload_handler.py

@@ -36,8 +36,9 @@ class UploadHandler:
         try:
             for root, _, files in os.walk(UploadHandler.image_directory()):
                 for filename in files:
-                    image_file = os.path.join(root, filename)
-                    uploaded_files.append(image_file)
+                    if not filename.startswith("."):
+                        image_file = os.path.join(root, filename)
+                        uploaded_files.append(image_file)
         except OSError:
             pass
         iourc_path = os.path.join(os.path.expanduser("~/"), ".iourc")