THRIFT-4343: enable nodejs-8.x on ubuntu-artful image and update grunt-jsdoc
also fix a perl failure as we were using a deprecated language feature
in the cross test server for perl.
Client: nodejs, perl

This closes #1406
diff --git a/test/perl/TestServer.pl b/test/perl/TestServer.pl
index c97067e..1e23ce8 100644
--- a/test/perl/TestServer.pl
+++ b/test/perl/TestServer.pl
@@ -282,7 +282,7 @@
         print(", ");
     }
     print("$key");
-    push($result, $key);
+    push(@arr, $key);
   }
   print("})\n");
   return $result;