Fixed permalink method to remove extra slash

The permalink already comes with a prefix slash, and thus it is not needed in the reddit domain name. (Fixes: "http://reddit.com//r/lisp/comments/2cs6qo/mocl_lisp_for_ios_android_and_os_x/" with http://reddit.com/r/lisp/comments/2cs6qo/mocl_lisp_for_ios_android_and_os_x/)