Moved the + and - signs to the data attribute so they can be overwritten using css.

git-svn-id: https://plugins.svn.wordpress.org/thumbs-rating/trunk@938259 b8457f37-d9ea-0310-8a92-e5e31aec5664
2.0 is ready !

git-svn-id: https://plugins.svn.wordpress.org/thumbs-rating/trunk@938262 b8457f37-d9ea-0310-8a92-e5e31aec5664