[RUBY] [CS] gather stuff into modules

new file:   ruby/change.rb
modified:   ruby/parentheses.rb
modified:   ruby/pascal.rb
new file:   ruby/rational.rb
[RUBY] implement Rational

basically transcoded the Scala version

modified:   ruby/rational.rb
[GO] [CS] ran `go fmt rational.go`

modified:   golang/rational/rational.go