Split the DataEntry into its numeric and string representation.
Add the necessary serialisation and deserialisation classes to handle numbers in items data.
Create a DataEntryBuilder and clean up the Deserialization
Completed serialisation/deserialisation of strings, numbers and booleans.
Added tests with strings, ints, doubles and booleans.
Simplify the specific *DataEntry classes by moving common behaviour into a common class
Merge branch 'feature/typed-value-serialization' into develop

Conflicts:
	src/main/java/de/fesere/hypermedia/cj/model/Query.java
Minor fixes after last careless merge