Add missing creator data to the account_created_operation vops

Closes #292 (closed)

No breaking changes were discovered: Impacted accounts are stored in the flat_set, which requires values to be unique and we implement setting same value for the new_account_name and the creator, but there will be one change: impacted accounts flat_set will change its size for the account_created_operation from 2 ("", "(account name)") to 1 ("(account name") (if I am correct)

Despite the above considerations, @bwrona please review