Working on feature activation lifecycle

Rationalizing some record names
Adding a shell feature concept, with Install and Enable states of rising/up/falling/down
Host has capability of firing a named event with an explicit configuration - needed for controlled execution of rising/falling state changes notifications

--HG--
branch : dev

src/Orchard.Specs/Bindings/OrchardSiteFactory.cs

@@ -44,7 +44,7 @@ namespace Orchard.Specs.Bindings {
                     var descriptor = descriptorManager.GetShellDescriptor();
                     descriptorManager.UpdateShellDescriptor(
                         descriptor.SerialNumber,
-                        descriptor.EnabledFeatures.Concat(new[] { new ShellFeature { Name = name } }),
+                        descriptor.Features.Concat(new[] { new ShellFeature { Name = name } }),
                         descriptor.Parameters);
                 }
             });