Upload new file
api/entities/upload
Method POST
Content-type: multipart/form-data
body
key=(file data)
where the key is a unique field for result
response
{ "status": "ok", "data": { "preview": "abc70d1d0139678300d17f4b992a220a" } }
preview is the key to an uploaded file
abc70d1d0139678300d17f4b992a220a is the generated ID that will be used in the entity update request