update climate parameter handling to correctly use trimmed down JSON files

[kemccusker]

The current approach relies on the user having access to a preprocessed climate parameter netcdf file (created from v1.0 JSON file of climate parameters).

PR #14 outlined a way to use the trimmed down v1.1 JSON files but left the implementation of preparing the params for a later PR. In looking into that implementation, I discovered that some v1.1 parameters have a different structure than the v1.0 parameters and so the implementation is not as straightforward as copying the code used to generate the netcdf file.

This Issue is meant to capture adding an implementation that can prepare the climate parameters xr.Dataset from v1.1 JSON files.