add python 3 support

README is updated to python 3
While this still functions correctly, there isn't a need to try and turn this into a list:

```>>> x = {'hello': 'world', 'testing': 'something'}
>>> for k,v in x.items():
...     print(k, v)
...
hello world
testing something
>>> for k,v in list(x.items()):
...     print(k,v)
...
hello world
testing something
```