Import error in pkg_resources.py
Pandas: 0.14
Python: 3.4
OS: Mac (installed through macports.)

```
import pyqtgraph as pg
import pandas as pd
```

running the above gives the following error (ImportError on cStringIO).

```
File "/opt/local/Library/Frameworks/Python.framework/Versions/3.4/lib/python3.4/site-packages/pkg_resources.py", line 50, in <module>
from cStringIO import StringIO as BytesIO
```

 To overcome this the following change (in line 51 pkg_resources.py)  seems to work

```
try:                                                                             
    basestring                                                                   
    next = lambda o: o.next()                                                    
    from cStringIO import StringIO as BytesIO                                    
except (NameError,ImportError):   
```
