Add something to the head() so a page can be identified

Add something to the head() so a page can be identified. Confluence doesn't really have the notion of special markup for title and author, as far as I know. If it does great - we need to support it in the Doxia parser. Even if it doesn't, the generated HTML needs to identify itself to a browser - could use the name of the Source for instance. Also the Doxia Book model likes to have some header meta data for a book. In the APT case it gets it from the header of the first section.