Allow YARN specific parameters to be specified

[costin]

In some cases, it is handier to allow YARN specific parameters to be specified through the command-line and thus have ES specific configuration. Some might be related to the memory settings while others might affect debugging (such as the obscure yarn.nodemanager.delete.debug-delay-sec and it's -1 value).

[costin]

YARN parameters that can be configured on the clients can be passed in through the Hadoop configuration used to start YARN itself. This seems to be the most convenient and generic method.