BKCtl does not respect -x option when creating stream znode

**BUG REPORT**

***Describe the bug***
When running ``` org.apache.bookkeeper.tools.cli.BKCtl --conf /conf/bookkeeper.conf cluster init -x ${CLUSTER_NAME} zk+hierarchical://${ZK_HOST}``` distributedlog and ledgers are created inside of /, but stream is created in root znode:

```
[zk: localhost:2181(CONNECTED) 3] ls /
[SERVERS, bookkeeper, stream, zookeeper]
[zk: localhost:2181(CONNECTED) 4] ls /bookkeeper
[distributedlog, ledgers]

```
***To Reproduce***
run ``` java ${OPTS} org.apache.bookkeeper.tools.cli.BKCtl --conf /conf/bookkeeper.conf cluster init -x ${CLUSTER_NAME} zk+hierarchical://${ZK_HOST} ```

***Expected behavior***

stream directory should be located under /${CLUSTERNAME}/stream

***Additional context***

Log of event:
```
[2019-03-14 15:28:21,277] INFO Initializing cluster bookkeeper :
ledgers : path = /bookkeeper/ledgers, uri = zk+hierarchical://zklocal-svc.default.svc.cluster.local:2181/bookkeeper/ledgers
dlog: path = /bookkeeper/distributedlog, uri = zk+hierarchical://zklocal-svc.default.svc.cluster.local:2181/bookkeeper/distributedlog
stream storage: path = /stream, num_storage_containers = 32 (org.apache.bookkeeper.stream.cli.commands.cluster.InitClusterCommand)
[2019-03-14 15:28:21,277] INFO Initializing cluster bookkeeper :
ledgers : path = /bookkeeper/ledgers, uri = zk+hierarchical://zklocal-svc.default.svc.cluster.local:2181/bookkeeper/ledgers
dlog: path = /bookkeeper/distributedlog, uri = zk+hierarchical://zklocal-svc.default.svc.cluster.local:2181/bookkeeper/distributedlog
stream storage: path = /stream, num_storage_containers = 32 (org.apache.bookkeeper.stream.cli.commands.cluster.InitClusterCommand)
```
Full log here:
https://gist.github.com/ca598880bb9e4e9b603404deda1ef36a