Check collection permission before upload

[TheJanzap]

I accidentally uploaded a file to a collection that doesn't let me add anything to it, so after the upload was done, I've recieved the following error message:
error uploading <file>: Access Denied - You lack sufficient privileges to write to those collections
It would be useful if this permission check could be made before uploading, so we don't have to upload twice (especially useful for larger files)