add not_tested config attributes

The shiny new build system respects the attribute #![cfg(not_test)].

I ignored all files that didn't make sense to have tests, building on the list in #58.  The primary motivation is we don't have to annotate **every** `fn` with #[cfg(not(test))].

Here's the script I used to convert files.
```bash
add_not_tested() {
    local source_file="$1"
    sed -i -e '2i#![cfg(not_tested)]' -e '/cfg.*not.*test)/d' "$source_file"
}

for f in "$@"; do
    echo "not testing $f"
    add_not_tested "$f"
done
```