[NEEDS REVIEW] Prevent updated parameters to be cached

This fixes bug for settings being cached after changes.

How to reproduce:
1. Turn on caching in Joomla
2. Enable global free leech
3. Button still says "Enable global free leech" until Joomla's cache is cleaned

My solution is a little bit dirty: simply clean system cache. I think there is a better alternative. Changing necessary setting in cache would be the best option.