Merge pull request #375 from iamqizhao/master

add the missing commit in previous PR
diff --git a/server.go b/server.go
index 049e809..ee44d1e 100644
--- a/server.go
+++ b/server.go
@@ -42,6 +42,7 @@
 	"runtime"
 	"strings"
 	"sync"
+	"time"
 
 	"golang.org/x/net/context"
 	"golang.org/x/net/trace"