Add caching

[alfg]

Identify areas that should be cached and cache them. We can use flask-cache and redis as a backend.

Some areas to consider:

• Context processors (such as homepage message)
• General static views

Also add a section in admin tools to reset cache and reset cache on Cloudflare.

[alfg]

Simply add the caching decorator to functions that need to be cached.

Example:

@cache.cached(timeout=100, key_prefix='display_notice')