Optimized upstream & loadbalancer

- Test and optimized load balancer origin picker
- Fixed no active origin cannot load proxy rule bug
- Implemented logger design in websocket proxy module
- Added more quickstart tours
- Fixed #270 (I guess)
- Fixed #90 (I guess)

src/mod/websocketproxy/websocketproxy_test.go

@@ -31,6 +31,7 @@ func TestProxy(t *testing.T) {
 	proxy := NewProxy(u, Options{
 		SkipTLSValidation: false,
 		SkipOriginCheck:   false,
+		Logger:            nil,
 	})
 	proxy.Upgrader = upgrader