Removed 'slowQueries', but we still need something

[tjayrush]

People who use the API from the command line complained about the way maxRecords and slowQueries worked (or a better description would be didn't work), so we remove slowQuery entirely.

The explorer relied on this to stay "snappy" when running against brand new addresses (already cached addresses didn't need it so much because 250 records (i.e. the default maxRecords) is fast enough.

Without slowQueries, the command line operates as it should, but the explorer is now a bit sluggish for new addresses.

To solve this, we can send "slowQueries` marker to the any API request and in the command line case, the user can do nothing, but in the explorer case, the explorer could ask for less records.

Slowqueries are -- identical to -- queries in which we have to do a reconciliation. Reconciliations take a long time.