Update encoding to UTF-8

src/Microsoft.ApplicationInsights.AspNet/ApplicationInsightsExceptionMiddleware.cs

@@ -1,4 +1,4 @@
-namespace Microsoft.ApplicationInsights.AspNet
+namespace Microsoft.ApplicationInsights.AspNet
 {
     using Microsoft.AspNet.Builder;
     using Microsoft.AspNet.Http;
@@ -33,4 +33,4 @@ namespace Microsoft.ApplicationInsights.AspNet
             }
         }
     }
-}
+}