Added some comments about the intent of interfaces

--HG--
extra : convert_revision : svn%3A5ff7c347-ad56-4c35-b696-ccb81de16e03/trunk%4039268

src/Orchard/Security/IAuthorizationService.cs

@@ -1,6 +1,10 @@
 using Orchard.Security.Permissions;
 
 namespace Orchard.Security {
+    /// <summary>
+    /// Entry-point for configured authorization scheme. Role-based system
+    /// provided by default. 
+    /// </summary>
     public interface IAuthorizationService : IDependency {
         bool CheckAccess(IUser user, Permission permission);
     }

src/Orchard/Security/IUser.cs

@@ -1,6 +1,9 @@
 using Orchard.Models;
 
 namespace Orchard.Security {
+    /// <summary>
+    /// Interface provided by the "user" model. 
+    /// </summary>
     public interface IUser : IModel {
         string Name { get; }
     }

src/Orchard/Security/Permissions/IPermissionProvider.cs

@@ -1,6 +1,10 @@
 using System.Collections.Generic;
 
 namespace Orchard.Security.Permissions {
+    /// <summary>
+    /// Implemented by packages to enumerate the types of permissions
+    /// the which may be granted
+    /// </summary>
     public interface IPermissionProvider {
         string PackageName { get; }
         IEnumerable<Permission> GetPermissions();