initial commit
* Add new methods
   * #each
   * #start_service
   * accessor to @emum & @tuple
* Add a new method "uri"
   * To use druby
* execute command "rspec --init"
   * initialize rspec
* Fix syntax error on spec_helper.rb
* Add most easy spec example
   * It is experimental so remove it in future.
* Add new methods "map" & "call"
* `require 'tapp'`
   * for using debug
* Add comment to experiment d_parallel
* Modify any method
* Modify "map" method for converving permutation of enumerable
* Create "client" class
   * The duty is to call block
* Replace "start_serivice" method in #map
* Call "DRB.stop_service" before DRB.start_service
    * prevent multiple start for DRb server
* Replace method `Enumerator#each` → `Enumerable#map`
* Forking process on "client"
* @tuple id is different from client's so that #map stop on #L25
   * It is experimental
* The @tuple reference is same client because return of BasicObject#__id__ method is same
   * It is experimental commit
* Rescue and return nil for exception of TupleSpace#write
    * slience that `_id2ref': xxxxx is recycled object (RangeError)`
    * It is experimental commit
* Refactor d_parallel.rb
* Use TupleSpaceProxy instance for transfer any objects
   * because it prevents vanishing any objects on tuple space