Code tidy-up: removed the "Models" namespace from the type name.
Add the 'Archetype.Courier' project.

Includes the Courier DataResolver for Archetype.
Refactored the DataResolver, as the underlying JSON value for the property had been modified (fields removed).
Code tidy-up; correct method naming; removed unused references
Separated out the extension methods into their own grouped classes.

Implements #172
Moved the `ArchetypePropertyModel.CreateDummyPropertyType` to an extension method.

With a view to re-use in the Courier DataResolver (as it does the same function).