附件下载支持调用SteedosBrower.downloadAndPreviewFile函数
Created by: baozhoutao
示例：
SteedosBrower.downloadAndPreviewFile({url: "https://qhd-beta.steedos.com/api/files/instances/qFWqxYFPEqm5pBZXK?download=true", caption: "test.docx", data:{id:"qFWqxYFPEqm5pBZXK", name:"test", extension:"docx"}})