ENH: Use Lambda and API Gateway to expose SageMaker endpoint

As a data scientist I want the SageMaker inference endpoint available outside of the notebook instance so that applications can get inferences on new samples anywhere.

## Acceptance criteria
- [ ] A client script can an Amazon API Gateway API action and pass parameter values.
- [ ] API Gateway passes the parameter values to a Lambda function.
- [ ] The Lambda function parses the value and sends it to the SageMaker model endpoint (i.e. the SageMaker Runtime Invoke_Endpoint)
- [ ] The model - as defined in the endpoint deployment - performs the prediction and returns the predicted value to AWS Lambda.
- [ ] The Lambda function parses the returned value and sends it back to API Gateway.
- [ ] API Gateway responds to the client with that value.