[WIP] Improve SDK

- [x] Allow more flexibility to configure guzzle cache plugin
- [x] Use virtual proxies, to remove dependency to entity manger in entities
- [x] Use annotations to describe mapping to the API fields
- [x] Redo hydration to get the benefit of proxies and annotation
- [x] Handle /me route
- [x] Handle extended API object graph
- [ ] Add command to generate proxies and annotation cache
- [ ] Unit tests