(PDB-4676) Allow caller to set FetchSize
(PDB-4676) Allow caller to set FetchSize

This commit allows callers to set the FetchSize in the call-with-query-rows
function. The setting controls the amount of rows that are fetched with each
database roundtrip for a given query. If unset it defaults to 500 rows.

puppetlabs/puppetdb,puppetlabs/puppetdb,puppetlabs/puppetdb,puppetlabs/puppetdb,puppetlabs/puppetdb