Support of new tranport layer for MailerQ (http://mailerq.com)

MailerQ (http://mailerq.com) is a high performance Mail Transfer Agent (MTA) designed for delivering large volume email messages at very high speeds. Relying on the industry standard, high availability message queue RabbitMQ, MailerQ offers maximum flexibility without compromise to stability or performance.

This pull request contains a new transport layer which enables you to send e-mails using MailerQ agent.