add new line after list

otherwise, during the html conversion the ul and li tags are not placed where
they need to go.

As per swcarpentry/lesson-template#140, but only the core CSS
changes.

Improve script to setup labels

Validator should check that required files exist

Use unified CSS from site.

As per swcarpentry/lesson-template#140, but with only the HTML changes

As per swcarpentry/lesson-template#140, but only the core CSS
changes.

- Delete GitHub's default label that will not be used
- Create new labels
- Update color for labels

Add debugging notes about Git and line endings

Import style for slides from https://github.com/swcarpentry/slideshows

Excluding unwanted files from build

(DO NOT CLONE) added adapted version of motivation.md that uses the pandoc slide generator and the new swc style

don't clone unless you know what you're doing (this commit will probably disappear)

- the "--slide-level 2" allows to generate consistent html structure
- one should only use "##" but never "#" for now

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/