requirements.txt better defaults

[Dan Masquelier]

Probably don't need flask boto, etc.
https://github.com/dancrew32/notebook/blob/master/requirements.txt#L12-L16

This one came up on the radar: pandas_profiling

https://towardsdatascience.com/exploring-your-data-with-just-1-line-of-python-4b35ce21a82d

Also worth adding Tensorflow/Keras