qemu-kvm: download debian images on https

no reason to use http

component/qemu-kvm/buildout.cfg

@@ -47,7 +47,7 @@ environment =
 recipe = hexagonit.recipe.download
 ignore-existing = true
 filename = ${:_buildout_section_name_}
-url = http://cdimage.debian.org/cdimage/${:release}/${:arch}/iso-cd/debian-${:version}-${:arch}-netinst.iso
+url = https://cdimage.debian.org/cdimage/${:release}/${:arch}/iso-cd/debian-${:version}-${:arch}-netinst.iso
 release = archive/${:version}
 download-only = true
 mode = 0644