remove db_rewrite_sql and views_data_alter in favor of a relationship handler

Related: #565076: Author message is displaying always four times for authenticated user role.

db_rewrite_sql() is causing bugs with DISTINCT and views_data_alter() pulls in the node table. If we just create a relationship to the node table instead we'll have our node access stuff in a more useful manner. db_rewrite_sql() was basically implemented as a way to retain node_access which a relationship handler can do for us.