Fix typing and update import for box
Fix typing and update import for box

- The type fix also finds a bug in our code where
  `._intra_move_copy_metadata()` calls a buggy
  `._get_folder_meta()` that further calls
  ._serialize_item() with invalid arguments.

felliott/waterbutler,RCOSDP/waterbutler,CenterForOpenScience/waterbutler