drive: fix subdirectory listing to not list entire drive - fixes #23
drive: fix subdirectory listing to not list entire drive - fixes #23

This was causing inexplicably slow transfers on subdirectories of
drives with lots of files.

greendayo7/rclone,arcimboldo/rclone,greendayo7/rclone,shalupov/rclone,seuffert/rclone,shalupov/rclone,arcimboldo/rclone,olihey/rclone,X1011/rclone,X1011/rclone,jackschmidt/rclone,klauspost/rclone,greendayo7/rclone,B4dM4n/rclone,simlelievre/rclone,shalupov/rclone,olihey/rclone,arcimboldo/rclone,klauspost/rclone,seuffert/rclone,kynikos/rclone,seuffert/rclone,alexcouper/rclone,ncw/rclone,jackschmidt/rclone,B4dM4n/rclone,kynikos/rclone,alexcouper/rclone,Blackfin/rclone,ncw/rclone,yonjah/rclone,yonjah/rclone,greendayo7/rclone,arcimboldo/rclone,Blackfin/rclone,seuffert/rclone,simlelievre/rclone,olihey/rclone,olihey/rclone,B4dM4n/rclone,jackschmidt/rclone,Blackfin/rclone,X1011/rclone,alexcouper/rclone,jackschmidt/rclone,yonjah/rclone,simlelievre/rclone,kynikos/rclone,yonjah/rclone,ncw/rclone,kynikos/rclone,ncw/rclone,klauspost/rclone,B4dM4n/rclone