Sign Instance
GET /data/api/signs/207/?format=api
http://labasi.acdh.oeaw.ac.at/data/api/signs/207/?format=api", "sign_name": "KAR", "abz_number": "376*", "meszl_number": "590", "image_1": "http://labasi.acdh.oeaw.ac.at/media/sign_img/kar_376..jpg", "image_2": null }{ "url": "