Change output file format

[jgwalkup]

Model output is currently exported in pickle format. To avoid issues with protocol compatibility and library dependencies, we should add an option to export data in another format (like csv).

[bioatmosphere]

In the long run, a format of netCDF may be a better option. CSV certainly works, but it would lose the appeal since the outputs of this model are of high dimensionality, which can go even higher. We could develop a separate functionality like those housed under the SPA folder in the current directory to do post processing.