html5 default to N

git-svn-id: https://plugins.svn.wordpress.org/wordprezi/trunk@987615 b8457f37-d9ea-0310-8a92-e5e31aec5664
params validation

git-svn-id: https://plugins.svn.wordpress.org/wordprezi/trunk@987618 b8457f37-d9ea-0310-8a92-e5e31aec5664