update sample.

samples/Sample.Kafka/Controllers/ValuesController.cs

 using System;
-using System.Collections.Generic;
-using System.Linq;
 using System.Threading.Tasks;
 using Cap.Consistency.Consumer;
 using Cap.Consistency.Kafka;

samples/Sample.Kafka/Program.cs

-using System;
-using System.Collections.Generic;
-using System.IO;
-using System.Linq;
-using System.Threading.Tasks;
+using System.IO;
 using Microsoft.AspNetCore.Builder;
 using Microsoft.AspNetCore.Hosting;
 
@@ -10,8 +6,7 @@ namespace Sample.Kafka
 {
     public class Program
     {
-        public static void Main(string[] args)
-        {
+        public static void Main(string[] args) {
             var host = new WebHostBuilder()
                 .UseKestrel()
                 .UseContentRoot(Directory.GetCurrentDirectory())

samples/Sample.Kafka/Startup.cs

-using System;
-using System.Collections.Generic;
-using System.Linq;
-using System.Threading.Tasks;
-using Cap.Consistency.Infrastructure;
-using Microsoft.AspNetCore.Builder;
+using Microsoft.AspNetCore.Builder;
 using Microsoft.AspNetCore.Hosting;
-using Microsoft.EntityFrameworkCore;
 using Microsoft.Extensions.Configuration;
 using Microsoft.Extensions.DependencyInjection;
 using Microsoft.Extensions.Logging;
@@ -27,7 +21,6 @@ namespace Sample.Kafka
 
         // This method gets called by the runtime. Use this method to add services to the container.
         public void ConfigureServices(IServiceCollection services) {
-
             services.AddDbContext<AppDbContext>();
 
             services.AddConsistency()
@@ -38,7 +31,6 @@ namespace Sample.Kafka
             services.AddMvc();
         }
 
-
         // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
         public void Configure(IApplicationBuilder app, IHostingEnvironment env, ILoggerFactory loggerFactory) {
             loggerFactory.AddConsole(Configuration.GetSection("Logging"));