Refactored ps_object formatting in the response.

  The previous code was calling the format class directly; whereas, the
  new code makes calls the PS::Base which get routed to the format
  class--look up tree wise. Code organization wise, the only methods
  that make calls to the format class is the PS::Api module, as is
  its responsibility. This refactor now puts a new constraint on format
  classes. They now must have 4 public methods, else the code wont
  function properly; those methods are as follows: initialize,
  request, date?, parse_date.
fixes 1
test for PS::Response
put spec files in proper subdirectories