Haskeleton: A Haskell Project Skeleton

- [x] Make headers consistent ("Testing" vs "Test Documentation").
- [x] Shorten Cabal output. It's not necessary to show all the output from `cabal test` every time, for example.
- [x] Edit, edit, edit. Paying particular attention to tense and first/second person nouns ("I" vs "you" vs "we").