changed equals and hashCode methods

- changed equals and hashCode method of LogicalTable
- changed equals and hashCode method of TriplesMap
different minor changes

- made abstract class TermMap a none-abstract class
- declared a method of the SubjectMap deprecated
- removed TODOs already done (R2RML2SMLConverter)
- whitespace cleanups in R2RML2SMLConverterTest
- removed empty setUp and tearDown methods in R2RML2SMLConverterTest
extended example triples maps
minor changes on R2RML2SMLConverter class

- whitespace cleanup
- removed useless method
renamed method in R2RML2SMLConverter
closes #5

Now R2RML graph map definitions are considered during R2RML-to-SML
conversion