[eclipse-poky] format and size of overlay icons?

[Tim Orling]

I have some of the original artwork necessary to create Yocto Project overlay icons (think the favicon when you are on a yp.org website). My thought is to make the “y” either black or grey and the “dot” will be the usual blue. Eclipse guidelines say that we should use blue, orange, yellow and purple. But we are not an EF project, so I think we keep with our own branding.