Introduce new kubelet volume manager

This commit adds a new volume manager in kubelet that synchronizes
volume mount/unmount (and attach/detach, if attach/detach controller
is not enabled).

This eliminates the race conditions between the pod creation loop
and the orphaned volumes loops. It also removes the unmount/detach
from the `syncPod()` path so volume clean up never blocks the
`syncPod` loop.

pkg/controller/persistentvolume/framework_test.go

@@ -980,14 +980,22 @@ func (plugin *mockVolumePlugin) Init(host vol.VolumeHost) error {
 	return nil
 }
 
-func (plugin *mockVolumePlugin) Name() string {
+func (plugin *mockVolumePlugin) GetPluginName() string {
 	return mockPluginName
 }
 
+func (plugin *mockVolumePlugin) GetVolumeName(spec *vol.Spec) (string, error) {
+	return spec.Name(), nil
+}
+
 func (plugin *mockVolumePlugin) CanSupport(spec *vol.Spec) bool {
 	return true
 }
 
+func (plugin *mockVolumePlugin) RequiresRemount() bool {
+	return false
+}
+
 func (plugin *mockVolumePlugin) NewMounter(spec *vol.Spec, podRef *api.Pod, opts vol.VolumeOptions) (vol.Mounter, error) {
 	return nil, fmt.Errorf("Mounter is not supported by this plugin")
 }