Update API to get baseline model

[rkemp101]

• [x] git pull origin gbq-setup
• [x] Update household_package.registry.load_model
• [ ] add options to save and load tensorflow keras model
• [ ] Update household_predictions.api.fast.py (predict function)
• [ ] Await preprocessing function from @dicanadu
• [ ] Update repo accordingly
• [ ] IF EVERYTIHNG FAILS: include mode pickle into the package and thus into the docker image