Fixed missing imports in classification_with_NODE notebook

[fonnesbeck]

The classificaiton_with_NODE notebook is missing a few imports and had several redundant and unused imports. This PR adresses these.

Fixes #33

[manujosephv]

Thank you for making the PR. But can you do one thing. Right now a lot of the notebook has been changed. If you can take the notebook, and only make the changes required to make the notebook run, but not actually run the notebook, it would be much better.

May be you can close the PR and open another one with just the import statements cleaned and make classification added?

[fonnesbeck]

Do you mean not show any output? Otherwise it would be strange to have inputs that don't correspond to the output. Why would you not want the model run with the inputs as they are changed?

[manujosephv]

oops.. my bad. I was having trouble checking the diff for notebooks...because it is usually messy.. Just checked the notebook in your fork and it looks fine. Merging the PR. Thanks for the contribution :)