Initial node drain implementation for #3885.

It cordons (marks unschedulable) the given node, and then deletes every
pod on it, optionally using a grace period.  It will not delete pods
managed by neither a ReplicationController nor a DaemonSet without the
use of --force.

Also add cordon/uncordon, which just toggle node schedulability.

pkg/kubectl/cmd/util/factory.go

@@ -673,3 +673,10 @@ func (f *Factory) NilClientMapperForCommand() resource.ClientMapper {
 		return nil, nil
 	})
 }
+
+// One stop shopping for a Builder
+func (f *Factory) NewBuilder() *resource.Builder {
+	mapper, typer := f.Object()
+
+	return resource.NewBuilder(mapper, typer, f.ClientMapperForCommand())
+}