* to_hash now only serializes attributes defined in the BaseEntity instead of all instance variables
* to_nested_hash leaves LazyEntityReferences unresolved
* Equality for LazyEntityReference and Version
Improved testability for LazyEntityReference
Merge pull request #33 from mcamou/master

to_hash now only serializes attributes defined in the BaseEntity instead of all instance variables;  to_nested_hash leaves LazyEntityReferences unresolved; Equality for LazyEntityReference and Version