mobile responsive design and many design fixes

adapt CSS to be either responsive, or specific to mobiles
add mobile menu icon to show the hidden menu on touch
add optimized language bar menu for mobiles
remove 1200px width workaround for the wallet page. Description now fit even on 1024x728 resolutions
remove links on wallet icons for :hover compatibility with mobile devices
move right buttons into the page
fix contributors plugin to produce W3C valid HTML
drop useless classes list .list
clean and organize CSS