Simplify website deployment

When the size of this website is getting larger, it is time to think of ways to speed up this website deployment.

This website was using rsync and rdiff-backup to deploy to web hosting server. The time to deploy the site is just getting longer.

Here are ways we did on this website to speed up the deployment:

• using Github Actions or Gitlab CI/CD
• host the images else where
• move source code files from listings folders to GitHub Gist

There are other steps taken during the process of speed up the deployment that doesn't related to speed:

• using two file format to seperate metadata and post
• using Markdown input format instead of reStructuredText
• using shortcodes as much as possible instead of plugins
• using the default theme
• the site is stripped-down

There are shortcomings after these steps are taken.

• The reStructuredText format supports a lot more HTML syntax by default. It is more developer friendly comparing with Markdown.
• Because of not using plugins, more condition logic are happen in shortcodes. In order to support Python code in template,
  Mako template is used rather than Jinja template.
• Unfortunately, the default theme dosn't pass the validation in Google structured data testing tool, due to missing required fields, 'image' and 'publisher' in 'Article' schema.
• More tidy up tasks are waiting to complete.