Built ability to add content to description and content:encoded elements


git-svn-id: https://plugins.svn.wordpress.org/rssupplement/trunk@928284 b8457f37-d9ea-0310-8a92-e5e31aec5664
Added content to <Description> and <cotent:encoded> 


git-svn-id: https://plugins.svn.wordpress.org/rssupplement/trunk@928287 b8457f37-d9ea-0310-8a92-e5e31aec5664