Broken render credentials flag for apiserver aggregator key

[mixecan]

Hi,
if I run kube-aws render credentials --help I get one flag without a name

    -- string        path to pem-encoded apiserver aggregator RSA key

The effect is that the render command replaces the apiserver aggregator key, even if I run

kube-aws render credentials -- credentials/apiserver-aggregator-key.pem

[dominicgunn]

This should be resolved now, see the attached PR.