[Table of Contens] Add CSS class for selected page number in Table of Contents addon.
Class: .table-of-contents-pagination .selected

Squashed commit of the following:

commit e12308ebf882121fcc3792c63f012a09942ce439
Author: Joanna Minakowska <joanna.minakowska@solwit.com>
Date:   Fri Feb 28 09:56:36 2014 +0100

    changelog

commit 0960b27152b191137472fc76b212e68649e78ad2
Author: Joanna Minakowska <joanna.minakowska@solwit.com>
Date:   Fri Feb 28 09:52:50 2014 +0100

    Add class to ToC