[tensowflow][mask_rcnn] mask-rcnn-inference.ipynb issues

https://github.com/awslabs/amazon-sagemaker-examples/blob/master/advanced_functionality/distributed_tensorflow_mask_rcnn/mask-rcnn-inference.ipynb

This notebook doesn't use default buckets and requires to much boiler plate to be filled by a customer making it cumbersome.

Open advanced_functionality/distributed_tensorflow_mask_rcnn/mask-rcnn-inference.ipynb and review how the notebook configures buckets and gathers customer inputs. Done means the notebook uses default buckets and requires less boilerplate for inference.

Written by the indexing model from the issue text.