Zip filename with spaces

Thank for the great work! It works in views easily, by following the instructions of VBO setup.

I setup the zip file with space characters in the file name. It works in Chrome, but the filename was trimmed when downloading through FireFox (3.6.10), e.g. "ABC gallery.zip" becomes "ABC".
Tried to add a double quote in header to workaround, and it looks good. So, attaching the patch and see if it should be added to the project.