Remove files using for Hakyll.
My site has been reborn.

I stop using the Hakyll because I would rather not `cabal install
hakyll`. It's taking too long time and sometimes building is fail.

And when I would like to write some post at other computers or new computer,
I have to `cabal install hakyll`. This is very troublesome above reasons.

Then I rebuild my site using Sinatra based on "入門 Sinatra" is being sold at O'Reilly.

English is turai.
入門Sinatra を参考にした旨を書いた
Merge branch 'new-version-using-sinatra'