change null author location to ZZ

After commit c744a1c7942276c644832ced5ffc18aa38768525, the
location tool now assigns the location_code "ZZ"
with the name "Unknown location".

For those `author/author_handle.json` whose
"location_code" and/or "location_name" was a JSON null,
they now use a "location_name" of "ZZ" and
a "location_name" of "Unknown location".

HELP: It would be nice if we could figure out the true location or at
      least a well justified guess of authors whose location is now "ZZ".
      We cannot simply use a guess based on the name.  But perhaps
      there are clues as to the current (or past) location of
      such IOCCC winner authors.

author/Neil_Mix.json

@@ -4,8 +4,8 @@
     "author_handle" : "Neil_Mix",
     "full_name" : "Neil Mix",
     "sort_word" : "mix",
-    "location_code" : null,
-    "location_name" : null,
+    "location_code" : "ZZ",
+    "location_name" : "Unknown location",
     "email" : null,
     "url" : null,
     "alt_url" : null,