Emit download_bytes param in spawned backends

Follow up to Follow up to c2eef57a63623b8bc439fd63d712f65a8d3fc847 and
736585f

It is up to the individual maintainers of the respective backends
to add support for this as required, as is it'll be reported as
'unknown'.

Author: joebonrichie

backends/entropy/entropyBackend.py

@@ -1140,7 +1140,7 @@ def get_details(self, package_ids):
                 continue
 
             self.details(pk_pkg, '', lic, self._get_pk_group(category),
-                         description, homepage, self._get_pkg_size(pkg))
+                         description, homepage, self._get_pkg_size(pkg), None)
 
         self.percentage(100)
 

backends/pisi/pisiBackend.py

@@ -171,7 +171,7 @@ def get_details(self, package_ids):
                 else ''
 
             self.details(pkg_id, '', ",".join(pkg.license), group, pkg.description,
-                         homepage, pkg.packageSize)
+                         homepage, pkg.packageSize, None)
         else:
             self.error(ERROR_PACKAGE_NOT_FOUND, "Package was not found")
 

backends/portage/portageBackend.py

@@ -966,7 +966,8 @@ def get_details(self, pkgs):
                 self._get_pk_group(cpv),
                 metadata["DESCRIPTION"],
                 metadata["HOMEPAGE"],
-                self._get_size(cpv)
+                self._get_size(cpv),
+                None
             )
 
             self.percentage(percentage)