add new options: --no_load_balancing, --randomize_suites
* split test suites into N tasks where N is the number of processors
* ensures that each sub process only processes one task
* when randomize_suites is enabled: suites are shuffled using optional
  seed argument
* make sure that exception thrown by workers are seen by master
add --resource_file option
* use a file to associate a command line argument to each ressource
* use a multiprocessing.Queue to manage the ressources between workers
* reduce the number of workers to the number of ressources (number of
  lines in the ressource file)