Allow option for table output when using python package to query

[bourque]

Currently the query() method in the python tool returns a list of dictionaries containing the results of the query. It would be nice to allow a user to pass some option (e.g. output='table' or output='df') that will return a pandas dataframe instead. Some users may prefer to work with a dataframe instead of a list of dicts.

[daralynnrhode]

Probably best to note this in documentation instead of adding to the code base. It is a fairly simply change that the user could do themselves.