Notes about storage systems
rclone: change "ls" and add "lsl" and "md5sum" commands

Changed "ls" command not to show modification time by default only
size and path.  That is because it is slow for nearly all the remotes
as it requires extra metadata lookup.  All remotes can look up files
and sizes without extra operations.

Added "lsl" which does what "ls" used to - namely show modification
time, size and path.

Added "md5sum" which produces the same output as the md5sum command -
md5sums and paths that is.
rclone: Don't purge if --dry-run set
drive: Fix comment