Remove unused uci_adult_dataset as confirmed by @keyvan-m-sadeghi in https://github.com/opencog/opencog/commit/0447e31a09525795cd3b3820d0fe9f535e86a03e#commitcomment-5063676
Merge pull request #519 from cosmoharrigan/python

Remove unused uci_adult_dataset as confirmed by @keyvan-m-sadeghi in: