refactor separate implementation from Cv module

  Cv::Core
    from http://docs.opencv.org/2.4.6/modules/core/doc/core.html
  Cv::Imgproc
    from http://docs.opencv.org/2.4.6/modules/imgproc/doc/imgproc.html
  Cv::Capi
    from C API
  Cv::Helper
    helper for RubyMotion