Move footer content from template into footer.html (FS#2847)

Users should be able to customize the footer without modifying the Dokuwiki default template.

The current Dokuwiki default template contains buttons and links in tpl_footer.php.  Removing or modifying this content requires changes to the template file. This is a bad approach because changes to the template will be lost after an upgrade.  

Here is an example of this bad advice: http://www.inmotionhosting.com/support/edu/dokuwiki/change-dokuwiki-appearance/removing-footer-buttons-text

Moving the buttons and text content from the template and into a user editable file ('footer.html') is a better approach that will still display the default buttons and text yet allow users to make changes that persist after an update.

Jon Jaroker
http://jaroker.com