Fix the download of file whose name contains space

Steps to reproduce:

1. on your personal computer, navigate to your user workspace
2. upload a PDF file whose name is test NXP.pdf
3. on your smartphone, browse the same application and authenticate.
4. follow the link to the newly created document
   # click on the Download link
   => Adobe Reader automatically tries to open the downloaded file but display an error : "Impossible to open this document, because it is not a valid PDF document"

The error does not occur if we do a long click and select "Save link as ..." and then open the downloaded file.