Changes

[Enhancement #96] Extend attribute mapping API with explicit datatype specification support.
 (commit: 4cb6781)

[Enhancement #96] Provide default value (empty string) for the datatype so that it is not required.
 (commit: ca5d9f7)

[Enhancement #96] Init attribute metamodel with explicit datatype.
 (commit: fa7d3b8)

Resolve most of the generics-related warnings in MetamodelMocks.
 (commit: eb614b9)

[Enhancement #96] Support namespace resolution for explicit datatype IRI specification.
 (commit: 00465e0)

[Enhancement #96] Add a representation of a literal with a lexical form and a datatype to the OntoDriver API.
 (commit: f40ec07)

[Enhancement #96] Implement mapping of OntoDriver Literal to the underlying storage literal representation.
 (commit: 0124860)

[Enhancement #96] Implement loading of unknown datatype literals to OntoDriver literal values.
 (commit: e742593)

Exclude log4j-slf4j-impl from Jena to have only the SLF4J for logging and let user choose which implementation to use.
 (commit: 8cd3f8a)

[Enhancement #96] Implement a converter for working with literals with explicit datatype.

Add basic integration tests for attributes with explicit datatype.
 (commit: f4882d6)

[Enhancement #96] Integration testing support for plural attributes with explicit datatype.
 (commit: 9e1356a)

[Enhancement #96] Provide additional explanation of the behavior of the ToRdfLiteralConverter.
 (commit: 18573cc)