Added Python code to calculate distance

This pull request has an initial conversion of the Java examples to Python. So far, just the distance calculations have been converted, but I'll start another pull request for each of the other directories. I tried to keep it as close in style to the Java examples, but as I'm learning these algorithms primarily from this code, I'm not too familiar as to what some of the arguments are (hence the lack of documentation at the moment).

Comments appreciated!