Cache contents to optimise load time and API calls

[tripu]

A page visit should not trigger a bunch of API requests every single time the same user visits it on the same client.

Some wild ideas:

• Client-side:
  • Web storage.
  • Web SQL DB.
  • Indexed DB.
  • Service workers.
  • Application cache.
  • Cookies.
• Server-side:
  • Configure W3C's servers to cache common API requests. The requests for the most common entities (probably: groups and specs) can be easily cached if we ignore the API key and assume there's not pagination, etc. I suspect that makes up a big chunk of the total number of requests the API will receive.