Refactor ansible prepare config (this will allow us to add control_driver in conf or to expose --control in cli easier)
Default values are in conf.yaml where the broker driver is mandatory for the task prepare
Now the cli changed to:
./cli.py deploy --driver=broker g5k # here the provider is mandatory
./cli.py test_case_2 --nbr_topics 10 {more options}
./cli.py campaign --provider=g5k test_case_2 # here the test case is mandatory
conf.yamlwhere thebrokerdriver is mandatory for the taskprepare