Ensure content_id_prefix is applied to parsely-page post_id

git-svn-id: http://plugins.svn.wordpress.org/wp-parsely/trunk@632344 b8457f37-d9ea-0310-8a92-e5e31aec5664
Add support for child categories as tags
Use explode not split
Remove unused option
Merge pull request #1 from Parsely/master

Updating.