add development_dependency "rake" and "bundler" gems into gemspec
Merge pull request #1 from shokai/fix_gemspec

add development_dependency "rake" and "bundler" gems into gemspec
* unify in String floor number
* bugfix of IIJHouse -> Iota
Merge pull request #2 from shokai/fix_iijhouse

specを全て満たすようにbugfix