Add Python3 Compatability

I've made some minor changes to support python3. 

1) Added parentheses to print states, since print statements are now the print function
2) Switched the imports from relative to absolute, since python3 handles relative imports differently
3) Dyanmically switched between xrange and range in python versions 2 and 3, since they are the same.

All of the unit tests still pass under python2.7 and python3. I don't have a python2.6 install available, but none of the changes should be incompatible.