Inherit is false in const_get DataValidator

* http://ref.xaio.jp/ruby/classes/module/const_get
"const_get A::B" uses only ruby 2.0

* http://spring-mt.tumblr.com/post/45097795854/ruby-2-0-const-get
Merge pull request #4 from SpringMT/ar-name-collision

Name collision For AR validator.