Working on references

The goal is to update *all* the document references that may exists of a given document
References

Now if a given document is updated, all their references' cache, if there is any, would also be updated. The update is done with `w` => 0 (write concern), so it doesn't wait up for a result
@ReferenceMany now works as @Reference
Merge branch 'feature/update-references' into develop