updating Code block evaluation messages

Thanks to Sébastien Vauban for suggesting these changes.

* lisp/ob.el (org-babel-insert-result): More informative code block
  evaluation messages.

lisp/ob.el

@@ -1504,9 +1504,9 @@ code ---- the results are extracted in the syntax of the source
 	  (indent-rigidly beg end indent))))
     (if (= (length result) 0)
 	(if (member "value" result-params)
-	    (message "No result returned by source block")
-	  (message "Source block produced no output"))
-      (message "finished"))))
+	    (message "Code block returned no value.")
+	  (message "Code block produced no output."))
+      (message "Code block evaluation complete."))))
 
 (defun org-babel-remove-result (&optional info)
   "Remove the result of the current source block."