New Project: reveal.js (slides) as proposed in #66
for slides:
data.json: name=slid.es instead of reveal.js, license and source set as suggested at https://github.com/libreprojects/libreprojects/pull/75#issuecomment-30303170
slides.png has margin of 48px each (160×160→256×256)
slides logo scaled to unified format 128×128 in 160×160 canvas
Merge pull request #75 from yuwash/revealjs

New Project: reveal.js (slides) as proposed in #66