Fix number of returned results
    
    When a filter for a tag is used, the number of returned items on a page
    did not match what was requested. This was caused by using an outer join
    with the tag/compose mapping table.
    
    However, the join is not needed, since the filter for tags is actually
    using nested queries:
    
        SELECT ... FROM composes
        WHERE NOT (EXISTS (SELECT 1 from tags_to_composes, tags ...))
    
    JIRA: RHELCMP-13392