Minimal example as test case.

[jasonbaldridge]

Make the minimal example work as a test case, similar to PrepAttachSpec.

Bonus: make the evaluation code a bit cleaner so that one isn't pulling out the label associations out of LabelSpecs, etc.

[jasonbaldridge]

Note that I haven't been doing branches until now since I just wanted to knock out a bunch of changes to get things kicked off, but I think now is the time to do things more cleanly -- so please do this as a branch with PR and assign it to me to review. Thanks!