Add weighted completeness metric worker
Add weighted completeness metric worker

I have added the weighted completeness metric worker which is more or
less the same code as the completeness metric code. I probably should
delegate some of the common code into the completeness metric only.

Signed-off-by: Konrad Reiche <4ff0213f56e2082fcd8c882d04c546881c579ce4@gmail.com>

platzhirsch/metadata-census