Commented Issue: HttpError should use case insensitive comparer [605]

The HttpError object should use a case insensitive comparer for determining key equality since the case of the dictionary keys cannot be guaranteed when sent over the wire.

For example, all our JSON properties are formatted using camelCase, so requesting HttpError.Messages actually looks for key "message", not "Message".
Comments: Fixed: https://aspnetwebstack.codeplex.com/SourceControl/changeset/4591296a44bc767c504398d4097de1446653c2fc