modified print statements in agents.py to make it work in Py3, changed utils_test.py with regard to new utils.py

This is from tmrts, pull request https://github.com/tmrts/aima-python/commit/4cc647ae3e1d4ab9a1fc4fc9be652f52b4e72851 , but I'm bad at git, so it was easier for me to merge by creating this file here.