Fix the OData feed on preview which was a) throwing null refs b) missing...

... a whole lot of data in fields (now that they are coming from Lucene instead of the DB) causing a blank UI to show once the throwing thing was fixed. Removed PackageIndexEntity class as it wasn't pulling much weight.

Fixes:
System.InvalidOperationException occurred
 HResult=-2146233079
 Message=The serialized resource has a null value in key member 'Version'. Null values are not supported in key members.
 Source=System.Data.Services
 StackTrace:
 at System.Data.Services.Serializers.Serializer.GetObjectKey(Object resource, DataServiceProviderWrapper provider, String containerName)
 InnerException: