cubicweb #2535715 Filename with space of quote are improperly exported to header [done]

For example a jungle babar.txt filename would be seen a will be exported as filename=jungle babar.txt an interpreted as jungle.

We need to quote this header parametes

priorityimportant
typebug
done in3.15.7
load0.500
load left0.000
closed by#b1145ad53999 [downloadable] fix filename HTTP header for simple name with space (closes #2535715)