Add drush command to translate

Problem/Motivation

Translating a huge amount of nodes could have a better performance if runned inside a Drush command.

Proposed resolution

Add a drush command to module.
ant_bulk:translate [anttrans]

Arguments:
type: Content type machine name to translate.
language: Language id to translate to.

Options:
--overwrite: Overwrite current translations defaults to false
--size: Batch size. All if ommited

Example:
ant_bulk:translate article fr --overwrite=true size=100