[3] Replace neighbors with distance vector

* Client's neighbors field replaced with
  distanceVector (which was already
  initially there) because the
  distanceVector map was going to have
  to include the neighbors anyways.

* isTest booean field added to Client to
  allow the passing in of flag to prevent
  excessive error messages from being
  printed when running unit tests.
Merge branch 'task-3-replace_neighbors_with_distance_vector'