Allow class on td and id and data-line-number on a
    
    This basically allows for elements added by the blame_loc
    filter to appear in the html since this html is passed through
    the bleach filter which limits the number of attributes an
    element can have.
    
    Incidentally, this commit also fixes the test suite
    
    Signed-off-by: Pierre-Yves Chibon <pingou@pingoured.fr></pingou@pingoured.fr>