Fix for Python 3.2 (Debian)

Before:
```python
>>> unshortenit.unshorten('http://adf.ly/WzXu2')
('http://adf.ly/WzXu2', 'expected bytes, not str')
```

After:
```python3
>>> unshortenit.unshorten('http://adf.ly/WzXu2')
('http://www39.zippyshare.com/v/69303767/file.html', 200)
```

Tested working on Python 2.7 and 3.4.  I can't test 3.3, but it should behave the same as 3.4.
Travis anyways will test 3.3.