Process newsletters deliveries asynchronously
Process newsletters deliveries asynchronously

We were seeing a timeout when queuing the 300.000+ emails to be
delivered

With this commit we are dealing asynchronously with this creations and
responding promptly, to avoid the web timeout of 30 seconds

AyuntamientoMadrid/consul,AyuntamientoMadrid/consul,AyuntamientoMadrid/consul,AyuntamientoMadrid/consul