Instead of renaming existing storage directories to a timestamped
format, create a timestamped directory in a temporary location and move
the individual files and folders inside storage directories to it. This
helps us with nested storage directories.
During the backup we create an intermediate copy of two directories:
builds and uploads. Instead of creating many small files with 'cp
-r', we now use tar (and fast gzip) to create single intermediate
files. This saves on disk IO and disk space while creating a backup.
