pagure-ev: Use Trololio instead of Trollius directly
    
    Trololio is a shim module that provides a Trollius-like
    interface to use Trollius or asyncio, depending on what is available.
    
    This will allow us to run pagure-ev on Python 3.
    
    Signed-off-by: Neal Gompa <ngompa13@gmail.com>
    
    Merges https://pagure.io/pagure/pull-request/3396