cleanup samples.

samples/Sample.RabbitMQ.MongoDB/Controllers/ValuesController.cs

 using System;
-using System.Collections.Generic;
-using System.Linq;
 using System.Threading.Tasks;
 using DotNetCore.CAP;
 using DotNetCore.CAP.Abstractions;

samples/Sample.RabbitMQ.MongoDB/Program.cs

-using System;
-using System.Collections.Generic;
-using System.IO;
-using System.Linq;
-using System.Threading.Tasks;
-using Microsoft.AspNetCore;
+using Microsoft.AspNetCore;
 using Microsoft.AspNetCore.Hosting;
-using Microsoft.Extensions.Configuration;
-using Microsoft.Extensions.Logging;
 
 namespace Sample.RabbitMQ.MongoDB
 {

samples/Sample.RabbitMQ.MongoDB/Startup.cs

-using System;
-using System.Collections.Generic;
-using System.Linq;
-using System.Threading.Tasks;
-using DotNetCore.CAP;
+using DotNetCore.CAP;
 using Microsoft.AspNetCore.Builder;
 using Microsoft.AspNetCore.Hosting;
-using Microsoft.AspNetCore.HttpsPolicy;
 using Microsoft.AspNetCore.Mvc;
 using Microsoft.Extensions.Configuration;
 using Microsoft.Extensions.DependencyInjection;
-using Microsoft.Extensions.Logging;
-using Microsoft.Extensions.Options;
 using MongoDB.Driver;
 
 namespace Sample.RabbitMQ.MongoDB
@@ -52,6 +45,7 @@ namespace Sample.RabbitMQ.MongoDB
             {
                 app.UseDeveloperExceptionPage();
             }
+
             app.UseMvc();
 
             app.UseCap();