fixed python3 compatibility 

```python
>>> import pypete
Traceback (most recent call last):
  File "/usr/lib64/python3.3/code.py", line 90, in runcode
    exec(code, self.locals)
  File "<console>", line 1, in <module>
  File "/.../pypete-0.1-py3.3.egg/pypete/__init__.py", line 3, in <module>
    from pypete import Pypete
ImportError: cannot import name Pypete
```