Merge pull request #48 from mcamou/master

Fixes to CTI
Extractes reference and attribute BaseValue methods to submodules
Fixed a potential Class.name method redefinition
Moved add_attributes to BaseMethods
Refactored Ids into Identifiers module
Added missing file in last commit. sorry
BaseEntity cleanup
marked set_version_attribute as private
Refactored GenericAttribute handling to DomainObject