BUG: refs #698. Send http 404 status if invalid bitstream id passed
BUG: refs #698. Send http 404 status if invalid bitstream id passed

To the download controller.

jcfr/Midas,jcfr/Midas,jcfr/Midas,jcfr/Midas,jcfr/Midas,jcfr/Midas