cleaned up some unused namespaces

Author: Mpdreamz

src/Nest/DSL/AliasDescriptor.cs

@@ -1,14 +1,9 @@
 using System;
 using System.Collections.Generic;
-using System.Globalization;
 using System.Linq;
-using System.Security.Cryptography;
 using System.Text;
 using Elasticsearch.Net;
 using Newtonsoft.Json;
-using System.Linq.Expressions;
-using Nest.Resolvers;
-using Nest.Domain;
 
 namespace Nest
 {