added css style for slides+webfont (taken from https://github.com/twitwi/deck.js-theme-builder)

It has been produced and can be updated with the following commands:

    git clone https://github.com/twitwi/deck.js-theme-builder tmpbuilder
    cd tmpbuilder/
    make
    cd ..
    cp tmpbuilder/software-carpentry.css css/swc-slides.css
    mkdir css/local-fonts
    cp tmpbuilder/local-fonts/zhcz-_WihjSQC0oHJ9TCYBsxEYwM7FgeyaSgU71cLG0.woff css/local-fonts/