Wrong index in driver.py file for model loading

[ashishrajsrivastava]

driver.py has wrong index 3 for model loading, however it should be 2. Using 3 its giving error `

python trainedModel = combine([trainedModel.outputs[3].owner])\nIndexError: tuple index out of range

I have used loop to determine the index and updated the index in driver.py file.

python for index in range(len(trainedModel.outputs)): print("Index {} for output: {}.".format(index, trainedModel.outputs[index].name))
Output

Index 0 for output: CE.
Index 1 for output: Err.
Index 2 for output: OutputNodes.z.

Will create a PR with changes i did.