Better size metrics

Currently, this is the what the tool outputs:
```
You've cleared approximately MB: 1292 or GB: 1 of space!
```
It is not proper English even and even less so - SI. It should be instead:
```
You've cleared approximately 1,292 MB or 1 GB of space!
```
And, yes, there should be a space after the number: https://www.engadget.com/2010/12/16/32-gb-versus-32gb-almost-everyone-is-writing-it-wrong/