Resultsdb - fix the pagination issue
    
    When `page=xyz` was not present in the URL the next/previous URLs were
    sometimes produced in the wrong way.
    Instead of checking for presence of other URL-encoded attributes `?page=1`
    was blindly added to the end of the URL string, while sometimes, it should
    have been `&page=1`.
    
    Differential Revision: https://phab.qa.fedoraproject.org/D1079