Article Microdata uses wrong @id property

[caendesilva]

Describe the bug
The Article element for posts currently have the wrong ID format.

To Reproduce
Steps to reproduce the behavior:

1. Run a compiled post through https://validator.schema.org/ to analyze the compiled data

Expected behavior
The current markup is <article id="post-article" , when it should be a unique ID to reference the actual post. For example, a post URI.

Current data:

Expected data:

Suggested implementation/fix
This is likely caused due to the Article styles being targeted using the #post-article. Replacing this with a CSS class would be better. Then we set the ID to posts/post-slug. If a site URL is set, we use that as a prefix, example: http://example.org/posts/post-slug