fixup! If there's a local copy of the MapIt Area data, use that

lib/mapit/wrapper.rb

@@ -45,26 +45,34 @@ def mapit_area_cache_filename(area_type)
       File.join('mapit', "#{URI.parse(mapit_url).host}-#{area_type}.json")
     end
 
-    def fetch_and_save(url, filename)
-      FileUtils.mkdir_p(File.dirname(filename))
+    def download_to_file(url, filename)
+      ensure_containing_directory_exists(filename)
       open(filename, 'wb') do |f|
         data = Net::HTTP.get(url)
         f.write(data)
-        data
       end
     end
 
+    def mapit_area_url(area_type)
+      URI(mapit_url + area_type)
+    end
+
+    def ensure_containing_directory_exists(filename)
+      FileUtils.mkdir_p(File.dirname(filename))
+    end
+
+    def ensure_downloaded(url, filename)
+      download_to_file(url, filename) unless File.file?(filename)
+    end
+
+    def parse_json_file(filename)
+      JSON.parse(open(filename, &:read))
+    end
+
     def areas_data(area_type)
-      # If the MapIt data is already cached in the filesystem, use
-      # that - otherwise fetch it from the server and save it.
       cache_filename = mapit_area_cache_filename(area_type)
-      if File.file?(cache_filename)
-        json_data = open(cache_filename, &:read)
-      else
-        url = URI(mapit_url + area_type)
-        json_data = fetch_and_save(url, cache_filename)
-      end
-      JSON.parse(json_data).values
+      ensure_downloaded(mapit_area_url(area_type), cache_filename)
+      parse_json_file(cache_filename).values
     end
 
     def cache_mapit_data