Bug 1072757 - Implement SettingsCore

I feel like we may consider using a real namespacing solution and instead using a string inside the namespace getter/setter. If we do this, we wouldn't need to set the SUB_MODULE_PARENT property.

E.g., ```
System.create('SettingsCore.SomeSubmodule');
// or possibly something like:
System.create('View.Dialog.ValuePicker');

// Alternate namespace approach:
System.namespace('View.Dialog') = ValuePicker;
```