Adjust logging and error handling in the client

* HTTP responses in the error range (400+) now properly turn into errors
* ROJO_EPIPHANY_DEV_CREATE now creates more verbose configuration
* Default configuration values are now much more explicit
* Errors that cause session termination are labeled more clearly.

plugin/src/HttpResponse.lua

@@ -31,4 +31,4 @@ function HttpResponse:json()
 	return HttpService:JSONDecode(self.body)
 end
 
-return HttpResponse
+return HttpResponse