remove ASP.net dependencies

@Benglin, `ComputationResponse.Nodes` is sent to and used by a client; Dynamo server doesn't need to use it anywhere. We can't use a stronger type than `object` in our current architecture `ExecutedNode` is inside of `DynamoCore` and `DynamoCore` has a dependency from `DynamoWebServer`. Probably it's not right and should be refactored. What do you think?