Edited Task: Move EntitySetController into System.Web.Http.OData.dll [419]

We should rework the sample EntitySetController from the samples into System.Web.Http.OData.dll

See: http://aspnet.codeplex.com/SourceControl/changeset/view/daeab2f8de6f#Samples%2fNet4%2fCS%2fWebApi%2fODataServiceSample%2fODataService%2fControllers%2fEntitySetController.cs