Server: check if server is running before closing it (Needs to be fix…

…ed after nodejs/node#4735)

lib/server.js

@@ -98,6 +98,12 @@ Server.prototype.destroy =
 Server.prototype.close =
 Server.prototype.terminate =
     function APIServer$destroy () {
-        this.http.close()
+
+        // Change this to `http.listening` once node supports it
+        // nodejs/node#4735
+        if ( this.http._handle ) {
+            this.http.close()
+        }
+
         this.redis.disconnect()
     }