Periodic runner refactoring

  'preiodic' runner renamed to rps (runs per second).
  Extensible pool of multiprocessing.Process was implemented instead
  of using constant length multiprocessing.Pool. That should decrease memory
  usage on large iterations and related errors.

Change-Id: I6e367ea30d89d5d0e7ba212ed22e8658421ac9bd
Merge "Periodic runner refactoring"