XD-1591: Flatten out ephemeral nodes

Containers that write out ephemeral nodes indicating deployment of a module previously used the following node structure for streams:

`/xd/deployments/streams/<name>/<type>/<label>/<container>`

This has been modified to look like this:

`/xd/deployments/streams/<name>/<type>.<label>.<container>`

This change will make it easier to create ZooKeeper watches on the stream to detect the addition/removal of modules and thus calculate the state of the stream.

It is recommended that existing streams and jobs in ZooKeeper are **destroyed** before using this change. Otherwise it is recommended to clear out the `/xd` path in ZooKeeper before usage.