Updating stores to use TypeDescriptor for type conversion

src/Microsoft.AspNet.Identity.EntityFramework/RoleStore.cs

@@ -3,6 +3,7 @@
 
 using System;
 using System.Collections.Generic;
+using System.ComponentModel;
 using System.Linq;
 using System.Security.Claims;
 using System.Threading;
@@ -160,7 +161,7 @@ namespace Microsoft.AspNet.Identity.EntityFramework
             {
                 return default(TKey);
             }
-            return (TKey)Convert.ChangeType(id, typeof(TKey));
+            return (TKey)TypeDescriptor.GetConverter(typeof(TKey)).ConvertFromInvariantString(id);
         }
 
         public virtual string ConvertIdToString(TKey id)

src/Microsoft.AspNet.Identity.EntityFramework/UserStore.cs

@@ -3,6 +3,7 @@
 
 using System;
 using System.Collections.Generic;
+using System.ComponentModel;
 using System.Globalization;
 using System.Linq;
 using System.Security.Claims;
@@ -212,7 +213,7 @@ namespace Microsoft.AspNet.Identity.EntityFramework
             {
                 return default(TKey);
             }
-            return (TKey)Convert.ChangeType(id, typeof(TKey));
+            return (TKey)TypeDescriptor.GetConverter(typeof(TKey)).ConvertFromInvariantString(id);
         }
 
         public virtual string ConvertIdToString(TKey id)

src/Microsoft.AspNet.Identity.EntityFramework/project.json

@@ -12,6 +12,7 @@
       "dependencies": {
         "System.Collections": "4.0.10-beta-*",
         "System.ComponentModel": "4.0.0-beta-*",
+        "System.ComponentModel.TypeConverter": "4.0.0-beta-*",
         "System.Diagnostics.Debug": "4.0.10-beta-*",
         "System.Diagnostics.Tools": "4.0.0-beta-*",
         "System.Globalization": "4.0.10-beta-*",

test/Microsoft.AspNet.Identity.EntityFramework.Test/UserStoreGuidKeyTest.cs

@@ -43,21 +43,11 @@ namespace Microsoft.AspNet.Identity.EntityFramework.Test
         public class ApplicationUserStore : UserStore<GuidUser, GuidRole, TestDbContext, Guid>
         {
             public ApplicationUserStore(TestDbContext context) : base(context) { }
-
-            public override Guid ConvertIdFromString(string userId)
-            {
-                return new Guid(userId);
-            }
         }
 
         public class ApplicationRoleStore : RoleStore<GuidRole, TestDbContext, Guid>
         {
             public ApplicationRoleStore(TestDbContext context) : base(context) { }
-
-            public override Guid ConvertIdFromString(string id)
-            {
-                return new Guid(id);
-            }
         }
 
         protected override void AddUserStore(IServiceCollection services, object context = null)