Tagged and released v2.3.3.

git-svn-id: https://plugins.svn.wordpress.org/pressbooks/trunk@994038 b8457f37-d9ea-0310-8a92-e5e31aec5664
Tagged and released v2.3.3.

git-svn-id: https://plugins.svn.wordpress.org/pressbooks/trunk@994040 b8457f37-d9ea-0310-8a92-e5e31aec5664