Add caching for performance gains

We make big efforts regarding performance improvements, and Passare is pretty solid overall, especially with the changes we made in the last couple of weeks.

However there are pages that we can't do much about them with traditional optimization, because they show a lot of information, or require a lot of different information at the same time. I would like to introduce caching into Passare, as it's something that the majority of large Rails applications depend on for performance improvements. Some of the techniques are described here https://guides.rubyonrails.org/caching_with_rails.html.

During the Hack Week my goal is to create a proof of concept, and have a system-in-place ready for future functionalities and/or existing slow pages. Here's my action plan:

Day 1: Do some research, and choose what part of Passare to work on, which will benefit from caching the most

Day 2-3: Implement caching methods and make sure that invalidating the cache works properly

Day 4-5: Do research on infrastructure requirements