mobile responsive design and many design fixes

[saivann]

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

[saivann]

This pull request can be viewed and tested live here : http://bitcoinmobile.zapto.org/

It covers at least three things that came back a few times in the feedback I received.

• Offer a good experience for mobile users.
• Move the right buttons into the page.
• Drop the 1200px wide workaround in the choose-your-wallet page.

@tcatm : Perhaps this can help with the bootstrap, as I've made many adaptation that goes in the same direction.

[saivann]

More feedback from an iPhone user might be helpful.
What I think needs to be tested the most :

• Tap to display the menu.
• Tap to display the description of each wallet in the choose-your-wallet page.
• Switching between languages.