Model versioning

[ardimirzaei]

Summary

Added metadata to the downloadable spreadsheet. Added version control for the downloaded data.

Smaller updates: Added a 'mailto' for the email link. Kept yearly forecasts as 4 years.

Related Issues

This addresses: #110 and #131

Checklist

• [x] The change is tested and works locally.
• [x] All related issues are referenced.
• [ ] Blog post included in PR if required e.g. new feature.

[ardimirzaei]

Example of the Excel output: