Removing response classes into their own files.

  modified:   libowl.gemspec
  modified:   libowl/client_world_connection.rb
  new file:   libowl/response.rb
  new file:   libowl/step_response.rb
Adding support for the cancel message in the request classes.

  modified:   libowl/client_world_connection.rb
  modified:   libowl/response.rb
  modified:   libowl/step_response.rb