Added versions, changelog and credits.

git-svn-id: https://plugins.svn.wordpress.org/thumbs-rating/trunk@922201 b8457f37-d9ea-0310-8a92-e5e31aec5664
GRRRR, it didn't commit 

git-svn-id: https://plugins.svn.wordpress.org/thumbs-rating/trunk@922202 b8457f37-d9ea-0310-8a92-e5e31aec5664