volume recycler: Don't start a new recycler pod if one already exists.

Recycling is a long duration process and when the recycler controller is
restarted in the meantime, it should not start a new recycler pod if there is
one already running.

This means that the recycler pod must have deterministic name based on name
of the recycled PV, we then get name conflicts when creating the pod.

Two things need to be changed:
- recycler controller and recycler plugins must pass the PV.Name to place,
  where the pod is created.

- create recycler pod with deterministic name and check "already exists" error.

When at it, remove useless 'resourceVersion' argument and make log messages
starting with lowercase.

pkg/controller/persistentvolume/framework_test.go

@@ -882,6 +882,9 @@ type mockVolumePlugin struct {
 }
 
 var _ vol.VolumePlugin = &mockVolumePlugin{}
+var _ vol.RecyclableVolumePlugin = &mockVolumePlugin{}
+var _ vol.DeletableVolumePlugin = &mockVolumePlugin{}
+var _ vol.ProvisionableVolumePlugin = &mockVolumePlugin{}
 
 func (plugin *mockVolumePlugin) Init(host vol.VolumeHost) error {
 	return nil
@@ -981,7 +984,7 @@ func (plugin *mockVolumePlugin) GetMetrics() (*vol.Metrics, error) {
 
 // Recycler interfaces
 
-func (plugin *mockVolumePlugin) NewRecycler(spec *vol.Spec) (vol.Recycler, error) {
+func (plugin *mockVolumePlugin) NewRecycler(pvName string, spec *vol.Spec) (vol.Recycler, error) {
 	if len(plugin.recycleCalls) > 0 {
 		// mockVolumePlugin directly implements Recycler interface
 		glog.V(4).Infof("mock plugin NewRecycler called, returning mock recycler")