Added the http status code into the errorcode structure

 Per Ryan's request, " @ryandrewjohnson  [5:58 PM] 
Thanks @xin-usa much appreciated. I've googled around to see what the typical http status code is for expired tokens and it seems it's a typical 401 unauthorized. So I'd most likely need to use the custom error code to differentiate between a normal 401 and a 401 from an expired token." 

@claylo :
I have added the http status code into the code structure. As we discussed during the weekend, we also see some best practice in adding the status code into the code structure, in order to refine the detail of errors. Let me know whether this looks okay. Thanks for writing up the venzee-error-handler module. It's fantastic!