Instead of returning a Family right away, make GenerateFunc return a
pointer to a Family, matching the convention across the k8s project and
removing the need to do so later in the code path.
Instead of defining the metric name both in the metric family generator
as well as the metric itself, with this patch the metric name is
injected into the metric family by the metric family generator.
This makes the rest of the packages useful to be used in a standalone
library without importing the kube-state-metrics specific collectors.
* Rename collectors -> collector package
* Rename metrics -> metric package
* Add metricFamily mocking in tests to prevent cyclic dependency.
tariqibrahim