ENH: allow groupby (and drop_duplicates) on columns containing unhashable types
#### Is your feature request related to a problem?

well sort of, currently one can not groupby on a column containing unhashable types (e.g dicts)

#### Describe the solution you'd like

an easy workaround is to groupby on that column as type str and then remap the strings back to their orig type,
wondering if we can provide this process built in so one can groupby on unhashable types if she desires to 

#### Describe alternatives you've considered

add a try except to allow hash(str(x)) in case hash(x) is impossible, or convert the column to str and add it back later

```python
# Your code here, if applicable

```
