Updating gh-pages

Made couple updates to this gh-pages.

Migrated to hakyll 4. Had a thought for doing this but haven't done for ... perhaps more than a year. As already mentioned, Compiler is not an instance of Arrow, instead an instance of Monad, Page and MetaCompilers have been removed, and couple more changes.

Replaced "8c6794b6.github.com" to "8c6794b6.github.io", since URLs for gh-pages have changed. According to User, Organization and Project Pages from GitHub Help, repository with *.github.io is the latest naming scheme.

Update 404 page, showing bigger lambda face now.

TAGGED: git, hakyll, haskell, web