Start french translation, full copy of English.
Set up french paths and global strings.
Translations by @PiRK from https://github.com/PiRK/learnosm/tree/9bcec78fd37babd7517e543ed2781649f87f24fc/_posts/fr .
Merge pull request #50 from hotosm/french

French translation - Traduction Françes
Merge pull request #49 from willemarcel/gh-pages

Partial revision of PT translation
add 404.html that redirects to /en/404.html, the users can switch language from there
Merge branch 'gh-pages' of github.com:hotosm/learnosm into gh-pages
Fix Arial -> Aerial. Thanks simonpoole.
Portuguese - total revision of start with OSM and partial of start with JOSM