ob-ruby: No longer require inf-ruby when no session evaluation takes place

* lisp/ob-ruby.el (org-babel-ruby-initiate-session): No longer require
  inf-ruby when no session evaluation takes place.

lisp/ob-ruby.el

@@ -128,8 +128,8 @@ Emacs-lisp table, otherwise return the results as a string."
   "Initiate a ruby session.
 If there is not a current inferior-process-buffer in SESSION
 then create one.  Return the initialized session."
-  (require 'inf-ruby)
   (unless (string= session "none")
+    (require 'inf-ruby)
     (let ((session-buffer (save-window-excursion
 			    (run-ruby nil session) (current-buffer))))
       (if (org-babel-comint-buffer-livep session-buffer)