tars a directory and rotates the backup files, deleting the oldest. The
BACKUP_LIMIT variable defines how many tar files files to keep.

Modules
		datetime glob os stat sys

Data
		BACKUP_LIMIT = 5 backup_dir = '/home/ut3hax/bin/tar_rotate' base_name = '-w' cur_backups = [] target_backup_file = '/home/ut3hax/bin/tar_rotate/-w-20091218.tar.gz' target_dir = '/home/ut3hax/bin/-w' today = '20091218'