This allows setting a prefix on the labels used to determine which
resources a series belongs to. The prefix may be set using the
`--label-prefix` flag.
This updates the dependencies to be compatible with Kubernetes 1.8,
including the new custom.metrics.k8s.io/v1beta1 API group and the
corresponding custom-metrics-apiserver changes.
Several of the unit tests were out of date with the interface or type
definitions. Now that we're running CI, they need to be up to date
(they should have been anyway, but that's a different story).
k8s.io/custom-metrics-boilerplate was "renamed" to
"github.com/directxman12/custom-metrics-boilerplate". This updates all
references to point to the correct location.
The initial functionality works. There's still a number of TODOs to
clean up, and some edge cases to work around, and some errors that could
be handled better.
