fixed mbstring support + sk translation

git-svn-id: https://plugins.svn.wordpress.org/tweet-old-post/trunk@962487 b8457f37-d9ea-0310-8a92-e5e31aec5664
fixed trans

git-svn-id: https://plugins.svn.wordpress.org/tweet-old-post/trunk@962488 b8457f37-d9ea-0310-8a92-e5e31aec5664