GroupBy Cleanup
Random Str formatting changes and removal of unneeded subclass overrides
Hello @WillAyd! Thanks for submitting the PR.

 - There are no PEP8 issues in the file [`pandas/core/groupby/generic.py`](https://github.com/WillAyd/pandas/blob/65c19992726d4d2478971dab16700116b5dc482f/pandas/core/groupby/generic.py) !

 - There are no PEP8 issues in the file [`pandas/core/groupby/groupby.py`](https://github.com/WillAyd/pandas/blob/65c19992726d4d2478971dab16700116b5dc482f/pandas/core/groupby/groupby.py) !

 - There are no PEP8 issues in the file [`pandas/core/groupby/grouper.py`](https://github.com/WillAyd/pandas/blob/65c19992726d4d2478971dab16700116b5dc482f/pandas/core/groupby/grouper.py) !

 - There are no PEP8 issues in the file [`pandas/core/groupby/ops.py`](https://github.com/WillAyd/pandas/blob/65c19992726d4d2478971dab16700116b5dc482f/pandas/core/groupby/ops.py) !

 thanks!