Review backups

[georgemillard]

• Remove stale craft backups
• Remove old manual backups
• Check we can restore from partial backups (eg NPEC)

/home/george/backups - 8.1 GB
/home/devs/site-backups - 10.6 GB
/var/www/ellenmacarthurfoundation.org/craft/storage/backups - 10.6 GB
/var/www/dif2015/craft/storage/backups - 1.3 GB