Fix for #185 zookeeper config format different than mesos. necessary?

Hi,

introduced a new parameter zk_marathon with desired format: zk://host1:port1,host2:port2,.../path
Deprecate zk_hosts and zk_state.
This change is backward compatible to current CLI.

ZookeeperConfTest added to ensure existing behavior remains valid and test new parameter is correct.

Cheers,
Matthias