Add cache for all DB queries

[neSpecc]

If widget will be injected at highload website, each visitor will provide request for counters.

So we need to remove influence of visitors to DB by adding a cache system.

1. Profile requests to BD
2. Add cache system
3. Integrate cache to each request to DB — set 10 mins cache.
4. Profile again, prove that all visitors got results from cache
5. When someone's makes a new reaction vote, invalidate cache and make new.