encog-java-core #194: NormalizationHelper is not serializable

This change addresses the issue at https://github.com/encog/encog-java-core/issues/194 : NormalizationHelper is not serializable.

This change includes making the following Serializable:
* NormalizationStrategy and its subclass BasicNormalizationStrategy
* Normalizer and its subclasses

This change adds a new unit test to verify serializability of NormalizationHelper: org.encog.ml.data.versatile.TestNormalizationHelper. 

To support the unit test, equals() methods were added to the following:
* ColumnDefinition
* Normalizer subclasses
* BasicNormalizationStrategy

Also, this pull request includes a trivial fix for encog-java-core #192: ColumnDefinition: default index should be -1. More detail:  https://github.com/encog/encog-java-core/issues/192 

All unit tests are green after these changes. A test build succeeded.
Unused import, breaks [the build](https://travis-ci.org/janisz/encog-java-core/jobs/42578492) on Java 6.