Option to switch between MiB and MB

[fabianmakila]

Originally was going to suggest switching back to the old ways of displaying used storage as MB seeing how MiB has caused a lot confusion since it's introduction. However some people might actually prefer the MiB approach.

So my suggestion would be to add a switch to the admin panel (or a config file) that defines in which format to show these.

[lancepioch]

This has been made into a pr!