Fixed server port being open after quit and date being 1970 if missing

Date wil be hidden if no set,
and of GEO data is also missing "Not available" will be shown under "Photo info"

server.py

@@ -264,5 +264,6 @@ class SlideshowHandler(http.server.SimpleHTTPRequestHandler):
 if __name__ == "__main__":
     os.chdir(os.path.dirname(os.path.abspath(__file__)))
     print(f"Serving slideshow on http://0.0.0.0:{cfg['PORT']}")
+    socketserver.TCPServer.allow_reuse_address = True
     with socketserver.TCPServer(("", cfg['PORT']), SlideshowHandler) as httpd:
         httpd.serve_forever()