Current site instance variable caching is causing caching issues in gobierto data

[ferblape]

current_site variable is an instance variable that is memoized to save database requests. When the variable is cached, the action site.datasets.cache_key is using the cached relation so the result is always the same. It's necessary to restart the Passenger to get a new clean instance variable.

Investigate if we can remove the memoization of the current_site, otherwise force the reload of the relation datasets.