Pipenv File & Unused Imports

[IanSaucy]

This PR removes unused imports in the predict module and adds a Pipefile for the entire package that reflects the package versions that where used to train and build the models.

This should help resolve issues such as those described in this ticket here: https://github.com/poke1024/bbz-segment/issues/2

In addition, take note of the h5py package version specification in the Pipefile this is due to the following issue: https://github.com/tensorflow/tensorflow/issues/44467

Users can now utilize Pipenv and simply the following commands to start working on the package:

pipenv update pipenv shell python [desired_module]

Also of importance is the python version, tensorflow==1.15 does not support python 3.8, hence the pinning of the python version in the Pipefile.