standardize on yaml configuration

[hokiegeek2]

Currently the configuration of Arkouda is handled by a mix of method parameters and environment variables, some of which are not documented in the README file. I recommend adding a yaml configuration file that puts all variables in one place. We can either parse the yaml file and set env variables or setup a singleton context object.

[mhmerrill]

@Bears-R-Us/arkouda-core-dev should we do this or close the issue?

[mhmerrill]

@hokiegeek2 so what tools would use the YAML file you are describing here? @joshmarshall1