func (c *Cluster) ImageLastAccessInit(fingerprint string) error {
	stmt := `UPDATE images SET cached=1, last_use_date=strftime("%s") WHERE fingerprint=?`
	err := exec(c.db, stmt, fingerprint)
	return err
}
func (c *Cluster) ImageLastAccessInit(fingerprint string) error {
	stmt := `UPDATE images SET cached=1, last_use_date=strftime("%s") WHERE fingerprint=?`
	err := exec(c.db, stmt, fingerprint)
	return err
}
//ImageLastAccessInit inits the last_use_date field of the image with the given fingerprint.