Sign Instance
GET /data/api/signs/227/?format=api
http://labasi.acdh.oeaw.ac.at/data/api/signs/227/?format=api", "sign_name": "ARAD", "abz_number": "50", "meszl_number": "18", "image_1": "http://labasi.acdh.oeaw.ac.at/media/sign_img/arad_50.jpg", "image_2": null }{ "url": "