[Review] Request from '' @ 'xystushi/git-review/review_130719_new_request'

Please review the following changes:
  * 54849be Early exist if no request id is provided.
  * d067688 Break down create command.
  * 7c1e42c Chage error class raised.
  * 229622f Break down prepare command.
  * f84801e Refactor clean command.
  * 22a6c4b Break down merge command.
  * 6c66941 Break down show command.
  * 8dfa755 Move up Errors by one level.
  * 6764a46 Break downd list command