Make run-hooks.sh slightly less noisy
run-hooks.sh installs hook runners correctly

It was treating the hook_name variable as a literal when it should have
been interpolating its value.
Tests actually have run-hooks.sh on PATH

I had thought they did before, since most of the tests were passing.

I was entirely wrong. $0 is *not* the name of the test suite in
bats (and there is no reason on earth why I should have expected it to
be, since bats is the running binary).

This commit stands as a testament to the difficulty of writing good
tests. Just checking for the expected exit status of 1 turned out to be
woefully insufficient.
Make tests check for expected output

Many of them used to just check the exit status of a commit command.

That turns out to be nowhere near sufficient - a lot of things can
terminate with a lot of different exit codes for a lot of reasons.
Remove setup from "runs without user hook package" test

The setup actually invalidated the test, at least a little bit.