Remove `404.html`

Providing a 404.html page doesn't make much sense for this project
as users will need to configure their server in order for the page
to be actually used.

In HTML5 Boilerplate, the idea is that the server configs (Apache or
the alternatives) will basically ensure that the user's server will
return the `404.html` page in case of an 404 error.

Also, with HTML5 Boilerplate, we've seen that users quite often forget
to change/replace the default 404 page.
Merge pull request #127 from alrra/remove-404-page

Remove `404.html`
Format .jshintrc in the same style as the code.

I noticed the .jshintrc uses tabs for indentation where main.js uses spaces, as does the
.editconfig specify to use.
Reindents main.js using two spaces.
Merge pull request #131 from jbnicolai/dev/format-main-js

Reindents main.js using two spaces.
Merge pull request #129 from jbnicolai/dev/format-jshintrc

Format .jshintrc in the same style as the code.
Uses document.querySelector directly, rather than wrapping it.

There appears to be no need to wrap it in a function, which only directly calls the querySelector itself.