Implement missing wordpress api

```
http://codex.wordpress.org/XML-RPC_wp

we miss

wp.getTags 
wp.getPageTemplates 
wp.deleteComment 
wp.editComment 
wp.newComment 
wp.getCommentStatusList 
wp.getCategories (maybe) 
wp.getComments 

that's all! 
```

Original issue reported on code.google.com by `walter.php` on 27 Aug 2009 at 3:31
