Entity Framework Core Migrations and Seeding

DalSoftDbContext.cs

using System;
using System.IO;
using System.Linq.Expressions;
using System.Reflection;
using Microsoft.EntityFrameworkCore;
using Microsoft.EntityFrameworkCore.Metadata;
using Microsoft.Extensions.Configuration;


namespace DalSoft.Data
{
    public class DalSoftDbContext : DbContext
    {
   
	public DalSoftDbContext(DbContextOptions options) : base(options) { }
        
        public DalSoftDbContext() /* Required for migrations */{ }

	protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
        {
            if (optionsBuilder.IsConfigured) return;

            //Called by parameterless ctor Usually Migrations
            var environmentName = Environment.GetEnvironmentVariable("EnvironmentName") ?? "local";
             
            optionsBuilder.UseSqlServer(
                new ConfigurationBuilder()
                    .SetBasePath(Path.GetDirectoryName(GetType().GetTypeInfo().Assembly.Location))
                    .AddJsonFile($"appsettings.{environmentName}.json", optional: false, reloadOnChange: false)
                    .Build()
                    .GetConnectionString("DalSoftDbContext")
            );
        }       
    }
}

ExampleSeedMigration.cs

using System;
using System.Collections.Generic;
using System.Linq;
using Microsoft.EntityFrameworkCore.Migrations;

namespace DalSoft.Data.Migrations
{
    /// <summary>Workaound for EF core not having Seed support https://github.com/aspnet/EntityFramework/issues/629 </summary>
    public partial class ExampleSeedMigration : Migration
    {
        
        protected override void Up(MigrationBuilder migrationBuilder)
        {
            using (var db = new DalSoftDbContext())
            {
                db.Apps.AddRange(new MyEntities[] {...});
                db.SaveChanges();
            }
        }

        protected override void Down(MigrationBuilder migrationBuilder)
        {
            using (var db = new DalSoftDbContext())
            {
               	db.RemoveRange(db.MyEntities)
                db.SaveChanges();
            }
        }
    }
}

Program.cs

using System;
using System.IO;
using Microsoft.AspNetCore.Hosting;

namespace DalSoft.Data
{
    public class Program
    {
        public static void Main(string[] args)
        {
            Console.Write("This is the workaround for:" +
                          "Could not invoke this command on the startup project. " +
                          "This preview of Entity Framework tools does not support commands on class library projects in ASP.NET Core and " +
                          ".NET Core applications. See http://go.microsoft.com/fwlink/?LinkId=798221 for details and workarounds.");

            new WebHostBuilder()
                .UseKestrel()
                .UseContentRoot(Directory.GetCurrentDirectory())
                .UseStartup<Startup>()
                .Build();
        }
    }
}

project.json

{
  "version": "1.0.0-*",

  "buildOptions": {
    "emitEntryPoint": true
  },

  "dependencies": {
    "Microsoft.NETCore.App": {
      "type": "platform",
      "version": "1.0.1"
    },
    "Microsoft.Extensions.DependencyInjection": "1.0.0-*",
    "Microsoft.Extensions.DependencyInjection.Abstractions": "1.0.0",
    "Microsoft.Extensions.PlatformAbstractions": "1.0.0",
    "Microsoft.Extensions.Configuration.EnvironmentVariables": "1.0.0",
    "Microsoft.Extensions.Configuration.FileExtensions": "1.0.0",
    "Microsoft.Extensions.Configuration.Json": "1.0.0",
    "Microsoft.Extensions.Options.ConfigurationExtensions": "1.0.0",
    "Microsoft.EntityFrameworkCore.SqlServer": "1.0.1",
    "Microsoft.EntityFrameworkCore.Tools": "1.0.0-preview2-final",
    "Microsoft.AspNetCore.Server.IISIntegration": "1.0.0",
    "Microsoft.AspNetCore.Server.Kestrel": "1.0.0"
  },

    "tools": {
      "Microsoft.EntityFrameworkCore.Tools": "1.0.0-preview2-final"
    },

    "runtimes": {
      "win10-x64": {}
    },

    "frameworks": {
      "netcoreapp1.0": {
        "imports": [
          "dotnet5.6",
          "portable-net45+win8"
        ]
      }
    }
  }

Startup.cs

using System;
using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Hosting;
using Microsoft.EntityFrameworkCore;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.DependencyInjection;

namespace DalSoft.Data
{
    /// <summary>EF core mirgations at the moment expects a Web startup and if we don't bootstrap it like this the -environmentName switch never gets populated. 
    /// I had to read the source to see why it wasn't working https://github.com/aspnet/EntityFramework/commit/7f48d0c0fca054ed70bebe0e8d2c58ee3cc3df9b</summary>
    public class Startup
    {
        private readonly IConfigurationRoot _configuration;
        private readonly IHostingEnvironment _hostingEnvironment;

        public Startup(IHostingEnvironment env)
        {
            var builder = new ConfigurationBuilder()
                .SetBasePath(env.ContentRootPath)
                .AddJsonFile($"appsettings.{env.EnvironmentName}.json", optional: false, reloadOnChange: false);

            builder.AddEnvironmentVariables();
            _configuration = builder.Build();
            _hostingEnvironment = env;
        }

        public void ConfigureServices(IServiceCollection services)
        {
            services.AddDbContext<DalSoftDbContext>(options =>
            {
                Environment.SetEnvironmentVariable("EnvironmentName", _hostingEnvironment.EnvironmentName.ToLower()== "development" ? "local" : _hostingEnvironment.EnvironmentName);
                options.UseSqlServer(_configuration.GetConnectionString("DalSoftDbContext"));
            });
        }

        public void Configure(IApplicationBuilder app)
        {
                
        }
    }
}

Is this intended to be used with EF 6.1.3 or only EF7?

Pay attention:
MigrationBuilder methods in "protected override void Up(MigrationBuilder migrationBuilder)" will be executed in the end, while "db.saveChanges()" will be immediately executed.
My situation:
I have to create a new model and seed data for it, I can't do it in a single migration.
I have to apply the creation in a previous migration and then apply a next migration with seed data