Failed ri2py conversion of Vectors.ListVector object to Python dictionary
Current conversion of R objects into Python usng `pandas2ri.ri2py` does not work for the `<class 'rpy2.robjects.vectors.ListVector'>` object. As noted [here](http://pandas.pydata.org/pandas-docs/stable/r_interface.html), `pandas2ri.py2ri()` and `pandas2ri.ri2py()` are current methods to handle conversion. However, previous deprecated  `com.convert_robj()` correctly converts the R object to Python dictionary:

``` python
import rpy2
from rpy2.robjects.numpy2ri import numpy2ri
from rpy2.robjects.packages import importr
import numpy as np

# FISHER EXACT TEST EXAMPLE
cont = np.reshape(np.arange(0,4), (2,2))  
statspackage = importr('stats',  robject_translations={'format_perc': '_format_perc'})
result = statspackage.fisher_test(numpy2ri(cont), simulate_p_value = True, B = 100)

# DEPRECATED CONVERSION
import pandas.rpy.common as com
pyresultdict = com.convert_robj(result)

print(type(pyresultdict))   # PYTHON DICTIONARY TYPE

# CURRENT CONVERSION
from rpy2.robjects import pandas2ri
pandas2ri.activate()
pyresultdict = pandas2ri.ri2py(result)

print(type(pyresultdict))   # REMAINS R LISTVECTOR TYPE
```

``` python
# Expected Output
<class 'dict'>
<class 'dict'>
```

```
# output of rpy2.__version__
2.5.4

# output of  pd.show_versions()
INSTALLED VERSIONS
------------------
commit: None
python: 3.4.1.final.0
python-bits: 64
OS: Windows
OS-release: 8
machine: AMD64
processor: Intel64 Family 6 Model 37 Stepping 2, GenuineIntel
byteorder: little
LC_ALL: None
LANG: None

pandas: 0.18.0
nose: None
pip: 8.1.0
setuptools: 2.1
Cython: None
numpy: 1.10.4
scipy: 0.17.0
...

```
