continue implement converter between Model(Jena) and GraphCollection with one NamedGraph( Singingframework)

- add support for Resource DataType when converting it into String for when creating Signingframework triple
- add input test file that contains objects with data types (for testing)
- change converter method signature to simplify the usage
- change ModelConverter tests not to hardcode graph name to be tested
finish implement converter between Model(Jena) and GraphCollection with one NamedGraph( Singingframework)

- use GraphCollection when converting without applying prefixes - solves errors resulting from how Signingframework applies prefixes
- improve ModelConverter test cases
- add test input that contains RDF without prefixes
- delete test input that is not used
- clean up ModelConverter code
implement Signer and Verifier that use Signingframework algorithm but Won approach to RDF with signature assembling

- do initial implementation of WonSigner and WonVerifier
- rename old Signer and Verifier to *Old
- implement test cases
- add RDF files for testing