Extract packaging -> Furoshiki

This removes packaging code from shoes4, and in particular, some huge files used in packaging. That code is now in the [shoes/furoshiki](https://github.com/shoes/furoshiki) codebase (see shoes/furoshiki#1).

Once furoshiki-0.0.3 is released, you will be able to `bundle install` and grab the packaging code. The only caveat is that you will need to have the shoes gem installed in order to package it:

```
cd shoes4
rake gem
gem install pkg/shoes-4.0.0pre1.gem
```

I suggest that we publish a furoshiki-0.0.3, then merge in this pull request.

Note that I made a few packaging improvements here (recently) after extracting the code, and those commits are not yet included in furoshiki.