test: Hadoop cluster and task config.

Add a 3-node cluster specification and a
task for running wordcount with Hadoop on Ceph.

Signed-off-by: Joe Buck <jbbuck@gmail.com>
Reviewed-by: Sam Lang <sam.lang@inktank.com>
suites: rados: multimon: add mon clock skews task yaml files

Signed-off-by: Joao Eduardo Luis <jecluis@gmail.com>