Move 'win32' files to contrib and packaging

This doesn't actually contain any "windows" code, and shouldn't be top
level anyway

Change-Id: I18843c1c67a91f1235b56bb1f100e3666bd1260a
Reviewed-on: http://review.couchbase.org/43693
Reviewed-by: Sergey Avseyev <sergey.avseyev@gmail.com>
Tested-by: Mark Nunberg <mnunberg@haskalah.org>