Add initial dependencies to gemspec
Add testing setup.
Add initial specs.
Add first implementation
Remove unused method
Inline update_foreign_object
Rename NoDefaultVocabularySetError to NoDefaultVocabularyError
Test IsomorphismAlreadyDefinedError message
Convert id_sym to just id
Rename subject to model_iri
Extract symbol manipulations.
'associated model' should be 'isomorphism'
Add type checking when setting the associated model.
Add delegation of associated model properties.
Add :delegation option to enable/disable attribute delegation.
Add documentation for isomorphic_with
Re-order method definition methods
Reset repository before each test
Guard against nil id
Add summary, description, homepage and README contents.