Upgraded Curator to 2.6.0
XD-1960 Module deployment upon new leader election

- Upon new leadership election, when the `ContainerListener` deploys
unallocated stream/job modules (via ArrivingContainerModuleRedeployer)
check for any existing deployments on the container in context.
 - If there are deployments on this container, then ignore the
container for unallocated module deployments given that this
container has already participated in module deployments.
 - Only caveat with this approach is that, since the
existing container may still have no deployments because of no
matching criteria, this would still run the unallocated module
deployments against this container (obviously no modules would be
deployed eventually).

This approach seems to work better than having some other logic
to compare against deployed modules of the same module type
for a given stream/job.

2nd commit message:

Fix code review comment

- Check for boolean to know if the arriving container has any
deployments instead of checking if the node is empty.
XD-1967 exclude hadoop installs from forceDependencies
Increase logging when running on travis
XD-1970 Improve Thread Naming for Rabbit Bus

JIRA: https://jira.spring.io/browse/XD-1970

Previously, all listener container threads in the
RabbitMessageBus had the same name.

This made it difficult to debug.

Use the queue name as the thread prefix so that you
can easily identify the module in the log.