glog.Warning -> glog.Warningf

[Miciah]

Fix two places where glog.Warning is used with a formatted string.

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[cadvisorJenkinsBot]

Can one of the admins verify this patch?

[vmarmol]

ok to test

[vmarmol]

thanks @Miciah! Could you sign the CLA when you get a chance?

[Miciah]

I work for Red Hat, so I should be covered by the corporate CLA.

[vmarmol]

Ah I see that. Thanks again! LGTM

[Miciah]

Thanks!