Improve DAS4 flexibility: just set the amount of nodes/instances you
want with das4_instances_to_run and the processes will get evenly
distributed. Also the sync_subscribers_amount var is now optional and
the experiment server will use das4_instances_to_run if not set.
Update all the experiments using das4_reserve_and_run
Merge pull request #64 from whirm/proces_conf_flexibility

Proces conf flexibility