- Homebrew Bundle referred to formulae as "brews". But it referred to
casks as "casks" and taps as "taps".
- Let's use the same terminology everywhere.
- (I know that `brew "hello"` is the formula syntax in the Brewfile, so
I'm not changing that (though would be up for it, in a backwards
compatible manner), just making the code more consistent.)
While we're here, also add `brew tests --no-parallel` which I relied
on during testing.
Pretty much anywhere we rely on a stubbed formula on disk to work: we
need to disable the API.