Add missing "line" in comments links
    
    When a user comments on a specific line of a pull request's file,
    Pagure describes that à la "$user commented on 31 of Makefile 2 months
    ago" with "31" referring to the line number.  Prior to commit
    1fa495df2d8ddc7094af4f5194db9ba3450b3d67, this would have read "$user
    commented on line 31 of Makefile 2 months ago".  This commit restores
    that syntax.