if we don't have a contenttype, use octet-stream
if we don't have a contenttype, use octet-stream

application/octet-stream is a generic MIME type, and basically means
"just download it, i don't know what type of file it is." I think this
is a nicer solution than not letting people upload the file in the first
place

ucdavis/Purchasing,ucdavis/Purchasing,ucdavis/Purchasing