Rolling backup scripts

Cron details:

# Each hour at 15 past the hour (keeping 72 versions)
15 * * * * /bin/bash /home/pledgeit/database_snapshots/backup_script_hourly

# Each day at 00:30 (keeping 14 versions)
30 0 * * * /bin/bash /home/pledgeit/database_snapshots/backup_script_daily

# Each month on the 1st at 01:30 (keeping 24 versions)
30 1 1 * * /bin/bash /home/pledgeit/database_snapshots/backup_script_monthly