Use of `log` in route

[bodhi]

@jinzhu I'm looking into standardising our logging (and not using log).

My first thought was to add a private field to Admin and func (Admin) SetLogger(), but the only place log is used is: https://github.com/qor/admin/blob/master/route.go#L371

Since the admin needs to be mounted to a http.ServeMux anyway, if you want to log QOR admin requests, you can do it via middleware around the mux, so the simpler option would be to just remove the log.Printf call?

[ZzEeKkAa]

Or still add SetLogger()