add kapost.getPreview and improved kapost.getPermalink

git-svn-id: https://plugins.svn.wordpress.org/kapost-byline/trunk@840464 b8457f37-d9ea-0310-8a92-e5e31aec5664
oops added missing file

git-svn-id: https://plugins.svn.wordpress.org/kapost-byline/trunk@840466 b8457f37-d9ea-0310-8a92-e5e31aec5664