clean up: remove unused namespaces

Disco.Data/Migrations/Configuration.cs

@@ -1,9 +1,6 @@
 namespace Disco.Data.Migrations
 {
-    using System;
-    using System.Data.Entity;
     using System.Data.Entity.Migrations;
-    using System.Linq;
     using Disco.Data.Repository;
 
     internal sealed class Configuration : DbMigrationsConfiguration<DiscoDataContext>

Disco.Data/Migrations/DiscoDataMigrator.cs

@@ -1,7 +1,6 @@
 using System;
 using System.Collections.Generic;
 using System.Linq;
-using System.Text;
 using System.Data.Entity.Migrations;
 using System.Data.Entity.Migrations.Infrastructure;
 using Disco.Data.Repository;