[gin] Retirement from GIN co-chair function

[Erwin Laure]

Dear GINers, 

As some of you probably already know I will be changing job in November
and this unfortunately means that I can't continue serving as co-chair
of the GIN-WG. 

It was a pleasure and very rewarding to work with you the past few years
and I hope the GIN-WG will keep up its momentum and drive Grid
infrastructures towards interoperable solutions. 

Best regards, 

-- Erwin