* Add new method #upload_to_s3
   * src expect path of file
   * dest expect path of directory
* Add `spec.add_development_dependency "rspec"`
* $ rspec --init
* Add new class `S3Utils::Path`
* Require lib/**/*.rb
* Add new spec S3Utils::Path.initialize
* Add new method #bucket_name
* Add S3Utils::Path#path_without_bucket and Refactor
* Add new methods S3Utils#path_without_bucket