Allow users to print full Request URL

https://github.com/justmao945/mallory/blob/ad32fd8abd0c4a763734717e762e2afae187fce5/server.go#L114


Change 
`L.Printf("[%s] %s %s %s\n", AccessType(use), r.Method, r.RequestURI, r.Proto)`
to
`L.Printf("[%s] %s %s %s\n", AccessType(use), r.Method, r.URL.String(), r.Proto)`

Or add a configuration option to do this. 