The files parameter in the above success callback function will be
an array of file objects, each with metadata about the selected file.
If multiselect is false, the array will contain a single item.
files = [{
"name": "file.txt",
"link": "https://...",
"bytes": 464,
"icon": "https://...",
"thumbnails": {"64x64": "https://...", "200x200": "https://..."}
}]