(feat) Set the status to 404 when no middleware handles a request.
(feat) Set the status to 404 when no middleware handles a request.

Fixes #95

fenhl/iron,markgeek/iron,dryganets/iron,dorfsmay/iron,bvssvni/iron,charsyam/iron,green-panther/iron,jlegendary/iron,leeric92/iron,beni55/iron,ilkosta/iron,lcqiang521/iron,tempbottle/iron,reem/iron,badboy/iron,youprofit/iron,shama/iron,shaunstanislaus/iron,Jeff-xchn/iron,lavriv92/iron,Undeterminant/iron,iron/iron,albperezbermejo/iron,armed/iron,steveklabnik/iron,graue/iron,ahwatts/iron,mzaccari/iron,mneumann/iron