Improve output provenance

[rickyegeland]

Information about what was used to produce sphinx results should be included in SPHINX outputs

For the reports:

• Include the version of SPHINX used to compute the results (from sphinxval.__version__
• Include the set of versions of the models that were evaluated, with a time range that each version covers (from the forecast jsons)
• Include the version of fetchsep that prepared the observations (from the observation jsons; to be added)
• Include the date or range of dates that the observations were prepared (from the observation jsons; to be added)

[ktindiana]

Could we make the version = date of the last change? Or the GitHub hash (can we know that automatically)? Or the version number is stored in the bin/sphinx.py file and is changed any time any of the routines within sphinx are changed? How do you propose we do the versioning? I have a problem with fetchsep versioning and I can change to whatever approach we take for SPHINX.