On a warm summer day, when you've got a couple of hours of golf ahead of you, there's no sight more welcome than the beverage cart. As it pulls up to the tee... with an attractive young lady at the wheel... golfers tend to smile. The prospect of an icy brew and a bit of lighthearted banter is always inspiring.But what's life really like for these peppy purveyors of on-course refreshment... and