Use npm test instead of trying to sniff for qunit in gruntfiles

[westonruter]

See todo in

wp-dev-lib/check-diff.sh

Lines 762 to 800 in 2e18d4e

	# @todo: This is wrong, as we should be doing `npm test` instead of calling `grunt qunit` directly.
	function run_qunit {
	if [ ! -s "$TEMP_DIRECTORY/paths-scope-js" ] || ! check_should_execute 'grunt'; then
	return
	fi
	find $PATH_INCLUDES -name Gruntfile.js > "$TEMP_DIRECTORY/gruntfiles"
	if [ ! -z "$PATH_EXCLUDES_PATTERN" ]; then
	cat "$TEMP_DIRECTORY/gruntfiles" | grep -E -v "$PATH_EXCLUDES_PATTERN" | cat - > "$TEMP_DIRECTORY/excluded-gruntfiles"
	mv "$TEMP_DIRECTORY/excluded-gruntfiles" "$TEMP_DIRECTORY/gruntfiles"
	fi
	if [ ! -s "$TEMP_DIRECTORY/gruntfiles" ]; then
	return
	fi
	for gruntfile in $( cat "$TEMP_DIRECTORY/gruntfiles" ); do
	if ! grep -Eqs 'grunt\.loadNpmTasks.*grunt-contrib-qunit' "$gruntfile"; then
	continue
	fi
	echo "Gruntfile: $gruntfile"
	# @todo Skip if there the CHECK_SCOPE is limited, and the dirname($gruntfile) is not among paths-scope-js; make sure root works
	cd "$( dirname "$gruntfile" )"
	# Make sure Node packages are installed in this location. Ignore symlink.
	if [ -e package.json ] && [ ! -e node_modules -o -h node_modules ]; then
	npm install
	fi
	if [ -e "$(npm bin)/grunt" ]; then
	$(npm bin)/grunt qunit
	else
	grunt qunit
	fi
	cd - /dev/null
	done
	}

For nested projects, should they use $( ls node_modules | wc -l ) == 0 like in #215?