DATAGRAPH-445: Added @Indexed(unique=true, failOnDuplicate=[true|false]) functionality
DATAGRAPH-445 Change to rather throw DataIntegrityViolationException instead of propagating raw ConstraintViolationException up
Aligned to use same versions of parent/sibling modules within multi module project
Merge pull request #192 from nickithewatt/DATAGRAPH-445

DATAGRAPH-445 Implement create_or_fail for GraphRepository