Improve binary star python example files

This pull request updates the binary star examples to support both Python2 and Python3, and makes the examples follow the Python coding standard, pep8. It also removes class instances from BinaryStar reactor class that also were set at instance level as data attributes.

Tested on both Python 2.7.5 and Python 3.3.2 on Ubuntu 13.10 with pyzmq 14.0.1 and zmq version 4.0.3.