adding woocommerce-category-best-seller-widget by steveostudios

git-svn-id: http://plugins.svn.wordpress.org/woocommerce-category-best-seller-widget/trunk@745894 b8457f37-d9ea-0310-8a92-e5e31aec5664
- Attempting to merge (again).

Merge remote-tracking branch 'origin/master'