Introduced Node/NodeListener classes

Added a Node class that provides functionality
for obtaining children and receiving notifications
of child additions and removals.

Improved ZooKeeperStandalone to guarantee that
ZK is running before returning from the start
method.

First usage of Oracle Tools Eventually.assertThat.
See the following reference for details:

http://coherence-community.github.io/oracle-tools/1.2.1/core/deferreds.html

Refactored ContainerServer to use Node and NodeListener
 Admin server functionality test

 Test to assert the ability of AdminServer to observe
 the number of ContainerServer instances in a cluster.
Improved ZK server detection
Renamed arrived/departed to added/removed.