* Improve account counters handling
* Use ActiveRecord::Base::sanitize_sql to pass values instead of interpolating them
Keep using string interpolation for `key` as it is safe and using
“ActiveRecord::Base::sanitize_sql_hash_for_assignment” would require stitching
bits of SQL in a way that is not more easily checked for safety.
* Add migration hook to catch PostgreSQL versions earlier than 9.5
