DATACMNS-357 - Added support for primitive ids in EntityInformation.

AbstractEntityInformation now detects primitive id types and adapts the isNew state according to the Java Language Specification §4.12.5. Supported are primitive Numbers and the entity is considered new if the value of the primitive field is zero.

Original pull request: #37.
DATACMNS-357 - Cleanups in primitive id detection.

Changed implementation in AbstractEntityInformation quite a bit to not need the non-final fields and a protected callback method. Cleaned up test cases to really test the new behavior, not the artificially introduced test helper class.

Original pull request: #37.