Another possible way to let Github Pages use the result of the custom converter.

This is another possible way.
Also this time, I recommend to check the commits one by one,
especially the second one is a little heavy.

By removing this kind of header of each textile,
```
---
layout: default
---
```

jekyll won't compile and serve the textile files directly,
instead the generated htmls are used.

The necessary procedures to update the site will be
```
$ ./script/generate_htmls
$ git add *.htmls
$ git commit -m "update the site"
```

Sadly, the working directory would look like this
https://github.com/ruby-hacking-guide/ruby-hacking-guide.github.com/tree/06ea5f5974ae109e8f23904e88c2a79ad97b6773

Since this structure could be inconvenient for translators and reviewers,
I think there's no need to hurry to apply this to master.

I just think I want a way to let Github Pages use the result of the custom converter
without changing the location of each textile file.