Fix missing character encoding and html lang tag. Refactor code
structure and missplaced elements.
Change script source for session.js to run locally.

Massive refactor to polish the code removing unused bits, changing
`var` for `let`, fixing insecure http protocol for https and fixing
architecture module that was broken because of a missnamed variable.
Rename cookie to a more significative name: `session-js`.

This property allows to track the session from external libs or a
backend. Once set, it will be written to the session and kept in the
cookie.

Create a switch named extra that when set records extra client
information. It was added from the demo page.

Feature/refactor