Create settings model and cell model

Created a model for the Settings data stored in the plist. Also created an abstract class for the table view cells so cell subclasses can be exposed and manipulated through one class
To better facilitate actually taking an action when one of these cells are chosen, this should accept an array of multiple choice model objects, with both a title and value. That will make it much easier to save the value of what item was chosen. But don't worry about that now - that will be a task for the next pull request.