create blog post presenter

created blog post presenter to take care of meta tags
initialized presenter in controller

added specs and initialized presenter inside controller.
changed the views to use the new presenter class
workaround blog_post_path error

workaround for the blog_post_path error. when calling
blog_post_path(blog_post) i get an error. the fix is a bit more
complicated. we should use the engine as a mountable engine otherwise i
don't think this should work. should look into it. open ticket 82475124