skinny 1.3.4 (new formula proposal)

This is new formula proposal. Skinny Framework is a famous web framework in Scala.
http://skinny-framework.org/
We already supports homebrew installation from our alternative repository for months past.
https://github.com/skinny-framework/homebrew-alt

Thank you in advance.
Strictly speaking, quite so. But I think globally installing [Yeoman](http://yeoman.io/) generators is common practice. Most users expect running global `yo` command anywhere (so `libexec/"skinny"` depends on global `yo` command).