Merge pull request #16 from Obvious/dpup-serverrequests

HTTPPool increments Group.Stats.ServerRequests
diff --git a/http.go b/http.go
index af329b5..ae69a63 100644
--- a/http.go
+++ b/http.go
@@ -130,6 +130,8 @@
 	if p.Context != nil {
 		ctx = p.Context(r)
 	}
+
+	group.Stats.ServerRequests.Add(1)
 	var value []byte
 	err = group.Get(ctx, key, AllocatingByteSliceSink(&value))
 	if err != nil {