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
It's good practice to ALWAYS use the super init pattern:

```
self = [super init];
if ( self ) {
   // init code here
}
return self;
```
This is because it's acceptable for an inherited initializer to return nil if something goes wrong.