new buttons xing and tumblr

git-svn-id: https://plugins.svn.wordpress.org/hs-social-media-buttons/trunk@909514 b8457f37-d9ea-0310-8a92-e5e31aec5664
update changelog

git-svn-id: https://plugins.svn.wordpress.org/hs-social-media-buttons/trunk@909515 b8457f37-d9ea-0310-8a92-e5e31aec5664