Updates to 2018/ferguson

Format changes in the README.md.

Update the test.sh and test-strings.txt files: modify the goodbye
message in the script (for fun) and add some fun strings for it to
search out.

2018/ferguson/test.sh

@@ -8,4 +8,4 @@ while read -r f; do
     # NOTE: ./weasel $* $f would just be the final word
     sleep 2
 done < test-strings.txt || exit 1
-echo "All done. Goodbye."
+echo "All done. Goodbye, you old monkeying weasel!"