[FIX] error message when genhtml is not in PATH
[FIX] error message when genhtml is not in PATH

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