Add a new section of exhibition_config to respond to the following URL, and return portions of the exhibition visibility information.

Example return:
url: exhibition_config/visibility/si-user:126
return:
{
"pid":"si-user:126",
"label":"randerson6",
"type":"concept",
"show_meta":true,
"children":[

{ "pid":"si:12345", "name":"Image 1", "type":"resource", "show_meta":false, "show_preview":true, "allow_download":false }

,{
"pid":"si:12346",
"name":"Incomplete folder, will hold more info later",
"type":"concept",
"show_meta":false,
"children":[

{ "pid":"si:12347", "name":"CSV filled with data", "type":"resource", "show_meta":true, "show_preview":true, "allow_download":true }

]
}]
}