Move scheduler code out of plugin directory.

This moves plugin/pkg/scheduler to pkg/scheduler and
plugin/cmd/kube-scheduler to cmd/kube-scheduler.

Bulk of the work was done with gomvpkg, except for kube-scheduler main
package.

cmd/hyperkube/kube-scheduler.go

@@ -20,7 +20,7 @@ import (
 	"flag"
 
 	"k8s.io/apiserver/pkg/server/healthz"
-	"k8s.io/kubernetes/plugin/cmd/kube-scheduler/app"
+	"k8s.io/kubernetes/cmd/kube-scheduler/app"
 )
 
 // NewScheduler creates a new hyperkube Server object that includes the