Improve Caching Mechanism

[masudm6]

From the feedback:

• Implement cache header setting/checking.
• Utilise HTTP cache response codes, such as 304 (Not Modified), where appropriate.

Notes and helpful stuff:

• https://medium.com/the-node-js-collection/simple-server-side-cache-for-express-js-with-node-js-45ff296ca0f0 (From 2017)
• When caching a request, we can also cache requests from similar routes (e.g. same location, but with both a cached postcode and a cached lat/long range.)
• https://www.npmjs.com/package/lru-cache (might not be appropriate)
• https://restfulapi.net/caching/
• https://sookocheff.com/post/api/effective-caching/
• (enjoying your holiday?)
• (hotel wifi is OP)
• (what does that even mean)
• https://stackoverflow.com/a/5823521 - Cache Control may take precedence over some headers

As a minimum, implement Cache-Control and ETags.
Then add expires-in and last-modified headers (for compatibility purposes with legacy clients)
Finally look into using something like redis to implement cacheing (or caching)

Side note: Cache - Cacheing or Caching?

An e at the end of a verb makes spelling things strange:

For some words it is obvious (think Dodge, Plunge), but for others it is confusing (specifically words ending with inge):
Binge - Bingeing or Binging?
Singe - Singeing or Singing? (!!)

For the word Singe, removing the e turns it into a different word altogether.
On the other hand, for words like bake and take, keeping the e just doesn't make sense. These all have a single consonant before final e.
For words with more than 1 consonant, like dance or wedge, removing the e is also the norm.
So despite the single exception listed at the start (for Singe), it seems that removing the e is preferred in these cases.

From this, I vote to remove the e. Caching.

Yet it still seems wrong ...