Sign Instance
GET /data/api/signs/216/?format=api
http://labasi.acdh.oeaw.ac.at/data/api/signs/216/?format=api", "sign_name": "URU", "abz_number": "38", "meszl_number": "71", "image_1": "http://labasi.acdh.oeaw.ac.at/media/sign_img/uru_38.jpg", "image_2": null }{ "url": "