Fix race condition in OpenIDConnect api
    
    Cherrypy seems to reuse objects if running in a multithreaded environment
    (e.g. mod_wsgi on httpd). This can result in multiple threads resetting
    attributes of OpenIDConnect api objects which then leads to various 500
    errors. A fresh cherrypy.request object is generated for every request,
    therefore it can be used to store these attributes safely.
    
    Related: #302
    
    Signed-off-by: Slavek Kabrda <bkabrda@redhat.com>
    Reviewed-by: Michal Konečný <michal.konecny@packetseekers.eu>
    Reviewed-by: Patrick Uiterwijk <puiterwijk@redhat.com>