XD-2004: Containers stopped responding to Admin

Fixed race condition between the container creating the
/xd/deployments/modules/allocated/container-id path and the
supervisor removing the path when the container exits.
The container will now wait for the supervisor to remove
the path before proceeding with startup.

Added onSuspend and onResume to ZooKeeperConnectionListener.
This allows us to distinguish between events where container
ephemeral nodes need to be created after a network disconnect.

Temporary network disconnects will raise SUSPENDED events
followed by RECONNECTED events. Containers will now avoid
undeploying modules upon SUSPENDED events. LOST events still
cause modules to be undeployed. RECONNECTED events will
force a re-registration with ZooKeeper if the connection
was previously LOST or if the container's ephemeral node is
no longer present.

Testing was done on Linux via iptables DROP rules.