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).
Use propertyAlias in fieldset validation

As described in #162 the umbracoPropertyAlias has been removed in favor
of a more unique propertyAlias. This propertyAlias should be used for
property identification in the validation.
Merge branch 'master' into pr/174
Merge branch 'pr/174'