Fix model download from marketplace

[tim]

From email to ajj:

After uploading the Pringle-Schmidt model for Ian to the SasView? marketplace online we discovered a small bug with the marketplace file downloader. Although if you click on the file link on the model description page (i.e. ​http://marketplace.sasview.org/uploads/8) it shows the file's contents, however, clicking the link at the bottom of the page returns a file that only contains the text:

'NoneType?' object has no attribute 'read'

I have tried this for models 2, 4, 6 & 8 all of which return the same file. Any ideas as to why this is occurring?

Regards,

Tim