org-mobile: Fix bug in mobile outline path handling

* org-mobile.el (org-mobile-get-outline-path-link): Use a `:' after
  file instead of a `/'.

lisp/org-mobile.el

@@ -648,7 +648,7 @@ The table of checksums is written to the file mobile-checksums."
   (org-with-point-at pom
     (concat "olp:"
 	    (org-mobile-escape-olp (file-name-nondirectory buffer-file-name))
-	    "/"
+	    ":"
 	    (mapconcat 'org-mobile-escape-olp
 		       (org-get-outline-path)
 		       "/")