IM: launcher.erl module upgraded (by @trons)

- New start/5 and start_bencherl/5 functions to run the different nodes on
  different hosts (one node per host). Note that client nodes are all
  launched within the same host, although this 'clients host' is dedicated.

- New stop/5 and stop/6 functions to stop the nodes. This is temporary,
  though. However, it will finish the IM nodes and only the IM nodes.
IM: Whitespace sync for toxic_client