Integer overflow in used space of user

[kholzapfel]

The report runs in an integer overflow for the "Disk space consumed by home storage in bytes." It maximally shows 2147483647 (2**32-1, max of int32) but works if the used storage is small than this.

Could be, that #19 (comment) wanted to point on this as well, as I am also using external storage as the primary location.