Removed unused usings, removed empty spaces, removed tons os warnings (#903)

test/Ocelot.UnitTests/Headers/RemoveHeadersTests.cs

@@ -1,7 +1,7 @@
-using System.Collections.Generic;
-using Ocelot.Middleware;
+using Ocelot.Middleware;
 using Ocelot.Responses;
 using Shouldly;
+using System.Collections.Generic;
 using TestStack.BDDfy;
 using Xunit;
 
@@ -49,4 +49,4 @@ namespace Ocelot.UnitTests.Headers
             _headers.ShouldNotContain(x => x.Key == "transfer-encoding");
         }
     }
-}
+}