Set proper response code when resource not found
Set proper response code when resource not found

For crossbario/crossbar#250

RaitoBezarius/crossbar,RaitoBezarius/crossbar,GoodgameStudios/crossbar,erhuabushuo/crossbar,erhuabushuo/crossbar,RaitoBezarius/crossbar,RaitoBezarius/crossbar,NinjaMSP/crossbar,RaitoBezarius/crossbar,RaitoBezarius/crossbar,erhuabushuo/crossbar,GoodgameStudios/crossbar,w1z2g3/crossbar,GoodgameStudios/crossbar,GoodgameStudios/crossbar,erhuabushuo/crossbar,w1z2g3/crossbar,NinjaMSP/crossbar,w1z2g3/crossbar,w1z2g3/crossbar,w1z2g3/crossbar,GoodgameStudios/crossbar,GoodgameStudios/crossbar,w1z2g3/crossbar,NinjaMSP/crossbar,RaitoBezarius/crossbar,w1z2g3/crossbar,erhuabushuo/crossbar,GoodgameStudios/crossbar,erhuabushuo/crossbar,erhuabushuo/crossbar