e2e SecurityContext tests wrong volume dir

The volume directory is not guaranteed to be /var/lib/kubelet
for a conforming implementation of Kubernetes.  Add --volume-dir
and an internal shim

test/e2e/util.go

@@ -139,6 +139,7 @@ var runId = util.NewUUID()
 type TestContextType struct {
 	KubeConfig            string
 	KubeContext           string
+	KubeVolumeDir         string
 	CertDir               string
 	Host                  string
 	RepoRoot              string