Set up post created subscription for blog type

Notification tab is empty for a content of type "Blog". One should be able to subscribe to

• Post creation, with the folowing notification template :
  A new post has been sent on one of the posts you subcribed to.(ndrl : ideally, we would like the title of the blog with a link to it) : <i>content of the post, html</i> To see this post in context and be able to comment : <i>link to the webengine url of the post</i>

A degraded mode waiting for the full feature would be to activate the default "content creation" subscription, which is not present currently.