Please don't drop pandas.rpy.common.convert_robJ
Currently pandas is the only well-known package supporting conversion from rpy2 object to dictionary.
There is warning message for rpy

```
warnings.warn("The pandas.rpy module is deprecated and will be "
              "removed in a future version. We refer to external packages "
              "like rpy2. "
              "\nSee here for a guide on how to port your code to rpy2: "
              "http://pandas.pydata.org/pandas-docs/stable/r_interface.html",
              FutureWarning, stacklevel=2)
```

Since the user primarily use rpy2 with pandas dataframe inputs, I strongly recommend keep this conversion functionality publicly available after rpy is retired. 

We will be very grateful !! 
