`static QuantityHelper()` a Weaving Candidate

[stiefeljackal]

When I keep looking at static QuantityHelper() as I go through the solution, I always think that it is a good candidate for weaving. To summarize what it does, static QuantityHelper() dynamically searches for Unit instances in IQuantity types and adds them to a list of accepted unit types. This entire process utilizes reflection. Although it it only called once as it is a static constructor, I still believe it is a good idea to weave in the collection of units instead.

There are probably better candidates within this repo for weaving, but I believe this is a good first one that can help setup a weaver for this repo.