Implement Memory unit (Scale & Format)

[PragTob]

For our (limited) memory conversion and formatting it feels to be the "right thing" to do (tm) to implement a unit with our existing Scale and Format behaviors in the Conversion namespace.

That wold get the unit specific knowledge out of the System module and lead to a more unified system. It might be a little bit of (implementation) overhead though, we could take a look at it to see how we could reduce that overhead.

[elpikel]

Working on it.

[PragTob]

Done in #131 🎉