support golang json marshal unmarshal api

most of the json.Marshal and Unmarshal scenarios are supported, if you find one that is missing feel free to open a ticket.

1. remove the dependency of json.Marshal/json.Unmarshal, use the marshaler and unmarshaler from our own. (cross check with json.Marshal and Unmarshal in unit test pass)
2. string option support for json tag, marshal & unmarshal
3. omit empty tag support
4. string option tag support
5. cyclic access detection during marshaling