Move poster_cache to the top of the module
Move poster_cache to the top of the module

Having a global between classes is a bit ugly.
Probably happened accidentally during a rebase..

ThiefMaster/indico,mic4ael/indico,mic4ael/indico,mic4ael/indico,OmeGak/indico,indico/indico,ThiefMaster/indico,indico/indico,pferreir/indico,DirkHoffmann/indico,pferreir/indico,pferreir/indico,ThiefMaster/indico,ThiefMaster/indico,DirkHoffmann/indico,OmeGak/indico,OmeGak/indico,mvidalgarcia/indico,mvidalgarcia/indico,indico/indico,mic4ael/indico,pferreir/indico,DirkHoffmann/indico,mvidalgarcia/indico,indico/indico,mvidalgarcia/indico,OmeGak/indico,DirkHoffmann/indico