Disable slim build

[taoeffect]

Problem

Recent changes by @corrideat have made it so that the full compiled contracts and their slim versions are about the same size.

If this is indeed so, there's no reason to build or load the slim versions, as it slows down the build time.

Solution

1. Verify the difference in size between the contracts. If it's negligible, proceed to the next step.
2. Update the build process so that a constant is defined at the top that specifies whether or not to build and sign the slim version.
3. Use this constant in the build process. When it's true, build and sign the slim version, when it's false, don't.
4. Verify everything works still and the tests pass.

[snowteamer]

Differences in size are indeed negligible: