v0.1.9

Version 0.1.9:

Refactor of the validation callback, adding more deafults mode of operation

Integration of a HPO (hyperparameter optimizer) to the polus lib
    - Implementing optuna as the default backend for HPO
    - Implementing a prune callback
   
Adding add_lookup_data to the CachedDataloader, which makes a conversion to the CachedDataloaderwLookup instance

Adding deep_copy method to CachedDataloader

Adding tutorials folder with python scripts for examples
    - Creation of a classifier_example

Adding more unit tests