Initial steps to python3 compatabilityPython3 compatability...

Made the necessary edits to get the example.py file to run on:
Python 3.3.2
matplotlib 1.3.1
pandas 0.12.0

Clearly more testing is required, but at least now the example file runs :)

Ammended: fixed bug where example data wouldnt load if run from
          different folder than ggplot/ggplot
merged file
Merge branch 'master' of github.com:yhat/ggplot
inc minor version