Auto JSON API generation & run specific generation code with args

[otterbotter]

https://trello.com/c/DA1Xr1A0/60-automate-json-api-endpoint-templates

This PR adds the following:

• Args to only generate specific sections of data (preview pages, treemaps etc.)
• Generate JSON API files for year-specific cases (preview pages, provincial/national budget phases etc.)
• Delete old JSON API financial years that are no longer in the current scope
• Fix jekyll syntax warnings during compilation

To generate specific sections only, use the following syntax:
python generate/from_dynamic.py --only {SECTION} {SECTION}
e.g. --only json_apis or --only json_apis treemaps etc.

For a list of available sections, use --help