feat(really-core): Implementation of Get/Read Handler
- Implement 'BETWEEN' operator in RQL
- Implement GET Request Handler
- Implement READ Request Handler
Merge pull request #8 from ashihaby/feat-readHandler

feat(really-core): Implementation of Get/Read Handler
feat(really-core): Handle reference fields on Collection Actor in case Create request

- refactor CollectionActor to be FSM
- fix test cases fro CollectionActor
- add reference filed
- implement CollectionActorTest to extend CollectionActor and handle test messages like `GetState`
- fix test cases for CollectionViewMaterializer, ModelLoader and GorillaEventCenter