Moar resource kinds

Now uses a kubectl get with a variable list of resources, see the kres.go for the entire list, and introduces a breaking change: only names params and no more arguments are supported.

So rather than (in 0.1):

$ krs dev42

You would now, in 0.2 do:

$ krs --namespace dev42

To specify resources that you want to track use --resources. For example, to track services and daemon sets:

$ krs --namespace dev42 --resources "svc,ds"

Initial release

This is an MVP, implementing basic stats scraping via kubectl get all and exporting the stats it in OpenMetrics format on stdout.