Add override for historical model base classes

Replaces #77

Added tests. Changed the override to an iterable per discussion with @treyhunner. Also added the ability to pass configuration arguments through the ```register``` utility to the ```HistoricalRecords``` constructor.
I doubt this sentence has significance to anyone outside of a select group of people.

I'm not sure this feature needs much explanation.  I assume if you need it, you'll know it.