- demonstrate `ModelMetadata` is available in a view
Also
- simplify `View()` overloads in `Controller`, pending #110 decisions
- make `Model` in `RazorView<T>` readonly
1. Areas defined by the Area attribute
2. Areas are a routeconstraint on the actiondescriptor
3. Areas find pages through route values
Other changes:
1. Remove Path from ActionDescriptor - It doesn't make sense with this change
2. Add sample Area
This is as simple as modifying the base class to return task and await the ExecuteAsync method. Also added a piece to the sample project to verify functionality.