Add a gallery

[aniawsz]

Make it possible to open a gallery of images on the website. Would be nice to have a separate page with pictures grouped into categories as well as be able to scroll through pictures on the article page.

Currently, we can't enlarge a picture added to an article. Ideally, after adding one or more pictures and clicking on one of them, it would show up as bigger and have arrows around it to scroll through all the pictures on the page.

[juskuz]

@aniawsz
I added enlarging a picture.
In three newest articles there is only one picture on the left. And it works fine. But for some articles (e.g. komitywa-hackathon/, openmeetings/, pyconpl-2014/ ) we have more than one photo. Then on the left there is a logo or something similar and the main picture (or pictures) is below the article (because it was added in *.rst file). How should it be working? The logo should be zoomed? Or we need change the newest articles?