1.0 release (for WordPress 4.0)

git-svn-id: https://plugins.svn.wordpress.org/onebox/trunk@978803 b8457f37-d9ea-0310-8a92-e5e31aec5664
added missing screenshot

git-svn-id: https://plugins.svn.wordpress.org/onebox/trunk@978824 b8457f37-d9ea-0310-8a92-e5e31aec5664