First model refactor

Move shared methods to a model base class, used the "augmented model base class" method from SQL Alchemy for this.

Created an alias for Base called Model, as sometimes it's more appropriate to use Model, while other times Base is preferred.  Either way, they are the same thing really.
More model refactoring

Model manager base class.

Note that we do still need to manually hook up the models to the model manager classes, I would like to automate this eventually when importing the models
Setup model manager instance by default