Prune function of copy mode causes problems with Screeps: Arena typings

[shanemadden]

prune function being enabled currently causes problems with deploying Screeps: Arena bots; the typings directory within user code directories for each arena is populated by the game, and (at least on the mac I've tested on) the prune function tries and fails to delete this directory with permissions errors. cargo-screeps should ignore that directory (or all directories?) when pruning.