React to Caching api changes

Author: kichalla

test/Microsoft.AspNet.StaticFiles.Tests/StaticFileContextTest.cs

@@ -6,7 +6,7 @@
 using System.IO;
 using Microsoft.AspNet.FileProviders;
 using Microsoft.AspNet.Http;
-using Microsoft.Framework.Expiration.Interfaces;
+using Microsoft.Framework.Caching;
 using Microsoft.Framework.Logging.Testing;
 using Xunit;