Add list of platforms/groups that are using OpenKnowhow

[amchagas]

I think it would be useful for visibility to add something like a grid of logos of platforms/groups already using Open KnowHow. This way we can easily point for newcomers who is already there and how they would benefit from joining too....

So far we have (please add as I don't remember them all!):
University of Bath
Richard's lab
Jeremy's lab
Sussex Neuroscience
Baden Lab
Euler Lab
Appropedia
BFOSH
Open Hardware Leaders

Maybe at the top, below the search bar, but before the projects? otherwise I'm afraid people will miss it if they don't scroll all the way down.

[kasbah]

Adding a grid of logos is probably better on openknowhow.org directly? We should add filters for organizations to the search as part of #25 though.