Twitter Streaming Initial code

For everyone's enjoyment I present the first bits of python-twitter's support for using the streaming API. There is still much work that needs to be done due to the nature of streaming, but this is a fun little merge that I think will get the ball rolling on the whole streaming thing. 

Here is a bit of sample code to try out. 

```python
for item in api.GetStreamSample():
    if item.has_key('id'):
        print item['id']
```
cntl-c will terminate the stream