include Wikimania group photo on people.wm.org

make the http://people.wikimedia.org startpage
look nicer, by... adding some people

use the Wikimania 2014 group photo for that,
it's the first association with Wikimedia and a lot of
people

the code i inserted is exactly what i get when following
the "use this image -> embed" links in MediaViewer :)

Change-Id: I6bcfff9aac6de9eb44e21a45a5a3f7d02565135a
Merge "include Wikimania group photo on people.wm.org" into production