(Slideshare) Adding slideshare plugins/slideshare

Made use of the plugin that is listed here:

https://github.com/petehamilton/Octopress-Slideshare-Plugin

In order to allow the easy additional of a slideshare based on the ID.
(RSS) Added new RSS Feed to default location

Coming from WordPress, it is expected that the RSS feed information is available at www.gep13.co.uk/feed, so added this option in.
(#1) Corrected pagination links

Changed paginator.previous_page to previous_page_path, same for next, and this corrected the issue.