Improved batch operations

Please see CHANGELOG.md for all changes.

The highlight of this version:

For each handler type (sync & async):

• getBatchDetails now has no limit to the size of the ip_addresses input
  list. It will chunk the list internally and make requests against the
  batch endpoint in a way that doesn't exceed the API's own limits.
• getBatchDetails now accepts the new options batch_size,
  timeout_per_batch, timeout_total and raise_on_fail. Please see the
  documentation for details on what each of these do.