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.
The backup restore code moves any existing uploads directory out of the
way before restoring the copy from the backup. If public/uploads was a
symlink, this move would replace the symlink. This commit avoids this
issue by first resolving any symlinks in the uploads path.
