empty __init__.py in tests/ so build passes in local repo

Finished porting to Python 3

This reverts commit 14c0cfe5.

Used tool 2to3 to finish the porting to Python 3 plus some fixes by
hand.

Fixed missing bracket in utils_test.py

Port and test text module for python 3.5

Link aimacode/aima-data repository as a git submodule

Agents.py

all  % string formating to .format is done in agents.py

Will add some kind of GUI later -- but this one didn't do much.

Enable continuous testing

Include MIT license

Add best practices for contributions

TODO (completed): Move >>> doctests from utils.py to utils_test.py